https://etalpykla.vilniustech.lt/handle/123456789/153434 Sun, 19 Apr 2026 11:50:09 GMT 2026-04-19T11:50:09Z https://etalpykla.vilniustech.lt/handle/123456789/160292 The evaluation of the efficiency of the l-shaped noise barrier while working with the programme CadnaA Venckus, Žilvinas; Grubliauskas, Raimondas Due to the diffraction of sound the idea to change the form of the barrier using various designs of the top edge of the barrier has become a very significant factor while increasing the acoustic effect of the barrier. Newly designed shapes of a barrier edge is a means helping to solve problems related to the construction of noise barriers, such as too high, inefficient barriers having no aesthetic appeal. Besides, models of a specially designed barrier edge might be adjusted to already constructed noise barriers to achieve greater efficiency. There are various barrier models: T-, Y-, U-, arrow, fork, and cylinder shaped barriers and so on. In this article the efficiency of the noise barrier is estimated using noise dispersion modelling programme CadnaA. A typical situation is being modelled: using a noise barrier with cantilever, calculations of noise levels are done shielding a linear source of noise. The impact of a barrier cantilever on noise dispersion behind the barrier depending on the direction and angle of its declination is being evaluated. While changing the direction of the cantilever declination („right“ or „left“), configurations of 90°, 130° and 160° angles were being modelled. In the noise suppression environment the features of noise dispersion appearing because of an obstacle, i.e., because of an impact of the noise barrier, are observed in vertical direction receding from the barrier in 1, 3, 6, 9 and 12 m distances, in 1-6 m height. Sat, 01 Jan 2011 00:00:00 GMT https://etalpykla.vilniustech.lt/handle/123456789/160292 2011-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/160291 Development of thermal insulation from local agricultural waste Vejelienė, Jolanta; Gailius, Albinas; Vėjelis, Sigitas; Vaitkus, Saulius; Balčiūnas, Giedrius In Lithuania yearly composes large quantity of waste during processing of agricultural plants. Large quantity of these waste amounts a straw. A small part of straw is used for biofuel, the remaining part of straw is chopped and injected in the soil. Purpose of this work is to explore possibilities for production of effective insulation material from straw. In this paper assessment of straw structure and technological factors on the thermal conductivity are presented. For the experiments straw of triticale were used. Thermal conductivity with different straw orientation and structure were measured. It was found that in the laboratory prepared samples has approximately 1.5 times lower thermal conductivity, in which majority of straw are oriented perpendicular to heat flow, than plant specimens prepared from straw bale and roll, in which majority of the straw are oriented parallel to heat flow. It was observed that increasing the density of loose straw thermal conductivity increases too, while thermal conductivity of chopped straw remains stable or declines slightly. Sat, 01 Jan 2011 00:00:00 GMT https://etalpykla.vilniustech.lt/handle/123456789/160291 2011-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/160290 Effect of precipitation on leachate parameters causing colmatation of landfill drainage layer Vasarevičius, Saulius; Bazienė, Kristina Municipal waste landfill drainage formatted at different stages of landfill exploitation, has a negative impact on natural environment. According to the newly implemented waste management policy, landfill drainage monitoring is being performed at solid waste disposal sites. In long time, complicated components of the filtrate destine sedimentation of part of the elements on the drainage layer. In this kind, porosity and layer penetration decrease. The principal elements influencing the decreasing penetration – calcium, iron, manganese and carbonate compounds. Filtration at landfills established from waste humidity and atmospheric precipitation penetrating through the waste. Systematic samples were determined by seasonality. Parameters analysed showed particularly higher values when precipitation amounts are lower and vice versa. Dependency of precipitation was proved by the statistical data analysis made with Pirson’s correlation coefficients. Sat, 01 Jan 2011 00:00:00 GMT https://etalpykla.vilniustech.lt/handle/123456789/160290 2011-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/160289 Manganese trends in tree rings of Pinus sylvestris L. – monitoring soil chemical changes Vaitkutė, Dovilė; Baltrėnas, Pranas Dendrochemistry can be used to monitor historical changes of the elemental composition in the polluted or undisturbed areas. In this study for analysis were taken the increment cores of Scots pine (Pinus sylvestris L.) from South – Eastern part of Lithuania. This region has one of the biggest pine forest areas in Lithuania, and was chosen to determine the background concentrations of manganese (Mn) in Scots pine tree rings. The particular analysis from uncontaminated areas may help to determine the elemental changes in tree rings at potentially polluted sites. Mn concentrations changes also could be used to reconstruct the pH historical changes in the investigated area soils. Current analysis results revealed that Mn concentration negatively correlated with soil pH and organic carbon, also slightly decreases from the tree heartwood to sapwood. Sat, 01 Jan 2011 00:00:00 GMT https://etalpykla.vilniustech.lt/handle/123456789/160289 2011-01-01T00:00:00Z