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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Apvaliosios ir smulkintosios medienos tūrio nustatymas svėrimo būdu / Measuring the bulk of logs and flaked wood by means of weighing it

Ažukas, Kastytis 15 June 2009 (has links)
Magistro darbe atliekama medienos tūrio nustatymo svėrimo būdu galimybių analizė. Darbo objektas – Apvalioji ir smulkintoji mediena naudojama medienos drožlių plokščių gamybai. Darbo tikslas - Ištirti apvaliosios ir smulkintos medienos, skirtos medžio drožlių plokštės gamybai, tankio kitimo dėsningumus ir jos svorio konvertavimo į tūrį ypatumus. Darbo metodai - Empirinio tyrimo metodas paremtas duomenų rinkimu medieną sveriant, atrenkant mėginius ir juos džiovinant. Kiekybinis palyginimas - statistinis duomenų apdorojimas paremtas dispersine ir regresine analize ir taikant koreliacinius ryšius. Visą empirinę medžiagą sudarė 180 medvežių imtis su spygliuočių, lapuočių ir smulkintoji mediena. Tiriama medienos tankio ir drėgnio koreliaciniai ryšiai, taip pat šių parametrų kintamumas nuo medžių rūšies, meteorologinių sąlygų: juos kertant ir sandėliuojant. Darbo rezultatai. Nustatyta, kad didžiausią įtaką medienos tankiui turi medienos drėgnis, o didžiausia drėgnos medienos masė yra žiemą. Pavasarį medienos masė mažėjo, o lengviausia buvo vasarą. Didėjant medienos santykiniam drėgniui, medienos tankis didėja nepriklausomai nuo medžių rūšies, tai rodo, kad medienos drėgnis ir jo kintamumas priklauso nuo metų laiko. Tiek lapuočių, tiek spygliuočių medienos masės priklausomybės nuo santykinio drėgnio kreivė žiemos metu yra aukščiausia, lyginat su pavasario ir vasaros kreivėmis. Tai dar kartą įrodo, kad mediena drėgniausia žiemos metu. Nustatytas drėgnio... [toliau žr. visą tekstą] / In this Master's paper an analysis is carried out to calculate the probability of estimating the volume of timber using the method of weighing. Work -study : Logs and flaked wood used for producing wood cutting panelling The aim of the work: Analysing the changes in thickness of logs and flaked wood used for producing wood cutting panelling and converting its weight into bulk. Methods of work: Empiric method based on weighing the timber, sorting out the samples and drying them. Quantitative analysis - processing the statistic data based on dispersive and regressive analysis and using correlation relations. The empiric analysis covered 180 trucks of softwood, deciduous wood and cutting.The correlation between the thickness and the humidity has been analysed. It has been also analysed how the thickness and humidity change in different species of trees, meteorological conditions, cutting down the trees and storing them. The results of the work: It has been decided that the greatest influence on the thickness of the wood has the density of the wood. The greater the relative density of the timber, the bigger the thickness of the timber. And it doesn't depend on the kind of the wood. It shows that the thickness of the wood and its changing depends on the season of the year. The curve of relative density in winter is the highest if ompared with the one in spring or in winter. The rate of the variation of density has been fixed from 11,5 to 32,2 %. As it is seen the range was great... [to full text]
2

Lietuvos medynų CO2 pasisavinimo ekonominė analizė / The Economical Analysis of CO2 Sequestration in Lithuania’s Forest Stands

Lapinskas, Marius 16 June 2006 (has links)
Study object. Forest stands in Lithuania: pine, spruce, birch, aspen, black alder, grey alder, oak, ash and others. Study aim. To estimate CO2 sequestration, to evaluate and to analyze its dependency on the main tree species, mean annual increment, age. Methodology. The estimations were made according to formulas stated in book “Algorithm of forest resources reproduction model (1984)”. The formulas allow to calculate CO2 stock per hectare in differrent tree species stands according to annual increment. Also by using Willis&Benson method and data based on calculations made by State Forest Survey Institute according to “IPCC Good Practice Guidance for LULUCF” methodology. Results. The biggest amount of CO2 is sequestrated in deciduous forest stands: by Zubas et al. method – 17,5 t/ha/year (coniferous – 14,2 t/ha/year); by Willis&Benson method – 10,3 t/ha/year (coniferous – 8,8 t/ha/year); by IPCC Good Practice Guidance for LULUCF method – 8,8 t/ha/year (coniferous – 7,4 t/ha/year). The age classes where annual increment is the highest sequestrate more CO2 than the ones with a lower annual increment. The total estimated value for the sequestrated CO2 of year 2002 in all the forest stands in Lithuania are as stated: by Zubas et al. method – 2,9 mill. Lt; by Willis&Benson method – 1,8 mill. Lt and by IPCC Good Practice Guidance for LULUCF method – 1,5 mill. Lt. For the warmhouse effect reduction the most valuable are tree species with the least economical value of wood... [to full text]

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