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Effects of timber loads on gross vehicle weight

75%
Forest roads are characterized by low traffic, but heavy timber haulage trucks have a significant influence on road conditions and usually exceed the limit of 80–100 kN per axle. The excessive weight of the trucks degrades the road surface and the forest environment. This article presents the results of a study of timber transport loads from their places of acquirement (forest districts) to the recipient (a large sawmill). The analysis includes the parameters of the timber transport vehicles and focuses especially on the gross vehicle weight (GVW), the total weight of empty truck and trailer during transport, and the weight of their loads. Scania, Iveco, Man, and Mercedes trucks with trailers and semitrailers designed for large-size pine timber transport were analyzed. ANOVA results revealed that all 80 analyzed vehicles exceeded the permitted GVW in the range from 2.28 to 19.94 Mg, transporting from 20.1 to 37.5 m3 of timber. The coefficient of determination between the amount of hauled timber and the GVW equaled 62.7%. Research conducted previously concluded that forest roads with ground and gravel surfaces are not suitable for overloads of 120–150 kN per axle. Therefore, it is necessary to find a logistical solution that will allow the load volume to be maintained at an acceptable level without destroying the forest road surface.
The causes of the eutrophication of Lake Jagiełek, situated around 6 km south-west of Olsztyn, were investigated in the hydrological years 1998-2004. The catchment area of this water body is situated in the watershed zone of the Łyna and Pasłęka rivers. The lake is subject to advanced eutrophication. As regards precipitation amount, the analysed period consisted of three dry years, two normal years and one wet year. Due to the occurrence of three successive dry years and higher evaporation resulting from increased air temperatures (by 0.5°C on average), the lake shallowed with periodic exposure of bottom sediments in the shoreline zone. The periodic exposure and inundation of sections of the lake bottom has led to intense mineralization of bottom sediments. This process contributes to secondary contamination of surface water with mineral substances, mainly nitrogen and phosphorus compounds. The investigated water body is situated in a watershed zone and is characterised by low and stable electrolytic conductivity (113 µS·cm-1 on average) and low pH of water (6.72 on average) which periodically reaches 4.70. The concentration levels of biogenic elements (nitrogen and phosphorus compounds) are subject to seasonal fluctuation. Relatively high concentrations of N-NO3 (1.25 mg dm-3 on average) were observed in the winter and spring, while low levels of this compound (0.18 mg·dm-3 on average) were reported in the summer and autumn. P-PO4 concentrations were marked by a growing trend from 0.26 mg· dm-3 on average in the spring to 0.70 mg·dm-3 on average in the summer. A high water load with biogenic elements, whose concentrations significantly exceeded the allowable and dangerous levels of N and P according to Vollenweider’s criteria, speeded up the eutrophication process and stimulated the gradual self-decline of the entire ecosystem. The restoration of ecological balance in the surveyed.
Studies on physico-chemical parameters of water in Czarna Hancza River and lakes Hancza and Wigry (North-East Poland) were carried out in 1991-1994 i.e. in the period of maximal pollution of this river-lake system. Basic information were obtained enabling explanation of high resistance of Lake Wigry to eutrophication. It was shown that co-precipitation of phosphates on calcite in the ecotone zone of Hanczanska Bay, where river waters mixed with lake waters, was an important process. Sedimentation of these substances in this lake part resulted in lower lake loading with phosphorus by as much as about 50%. The mechanisms were operating most of all during the vegetation season, when water pH exceeded 8.3. Availability of phosphorus to phytoplankton depended also on phosphate release from bottom sediments. The lowest rate of this release was observed in Hanczanska Bay. On the other hand, in autumn and winter the increase of organic matter decomposition and lowering of water pH enabled free spreading of pollutants over the whole lake.
Omówiono budowę i działanie maszyny do dwufazowego zbioru wierzby krzewiastej. Przedstawiono wyniki badań symulacyjnych dotyczących wpływu położenia dyszla transportowego na obciążenia kół jezdnych maszyny. Przedstawiono wyniki przeprowadzonych symulacji w postaci graficznej.
20
38%
Ziemniak Polski
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2004
|
tom 14
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nr 3
33-36
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