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A study in the years 1978-1982 and 1992 took place in 11 towns covering 263km² and 6 areas of farmland covering 560km². Magpies were found to inhabit all of the towns in the 1970s and 1980s, at population densities ranging from 0.05-3.1 pairs/km² (mean 1.5). Mean breeding densities were 3.6 and 0.9 pairs/km² in urban and suburban areas respectively. In the years to 1992 the breeding population in towns increased 88%, with 1992 densities varying between 0.3 and 4.5 pairs/km² (mean 2.8). The increase was much more marked in urban areas (129.5% to a mean of 8.2 pairs/km²) than in the suburbs (up 35% to 1.2 pairs/km² on average). Rural populations were dominated by village-dwelling Magpies (respectively 60% and 76% of the breeding populations in 1979-82 and 1992). Nesting densities on farmland remained in the range 0.2-1.8 (mean 1.0) pairs/km² throughout the period, with increases being confined to villages (12.4 pairs/km² 1979-82, cf. 21.3 in 1992) and neighbouring farmland showing a 13% decrease. It is concluded that the ecological success (i.e. increased numbers) of Magpies is a consequence of progressing synanthropization and synurbization.
The height, chosen tree species and location of 1316 Magpie nests in 11 towns and 6 farmland plots were examined in 1992. t-tests revealed a difference significant at p < 0.001 for the heights at which nests were located, with those in urban areas (x̅ = 13.2m, SD = 3.7, N = 513) being higher than those in suburban areas (x̅ = 11.3, SD = 4.1, N = 232), those in villages (x̅ = 9.6, SD = 3.7, N = 433) and those on farmland (outside villages) (x̅ = 9.0, SD = 3.7, N = 138). The heights of nests in villages and on farmland outside villages did not differ significantly. The percentage distribution of chosen trees showed a predominance of similarities (using Renkonen's Index) for the biotopes compared: urban and suburban areas (Re = 73%), villages and farmland outside villages (Re = 77%). The percentage distribution of nest locations (single trees/shrubs, clumps of trees/shrubs, parks/cemeteries, gardens/orchards, avenues, rows of trees/hedgerows) also showed a predominance of similarities for urban areas, suburban areas, villages and farmland outside villages (Re values between 75% and 85%). The data indicate substantial ecological plasticity in the selection of nest sites by Magpies and suggest that differences are due to local variations in nesting habitat rather than real differences between urban and rural populations.
The paper presents shallow water experiments of a self-propelled, free running model of an inland water motor barge. In accordance with the Rhine Manoeuvring Standards Rheinschiffsuntersuchungsordnung (RheinSchUO 1995, issue 2005), evasive action manoeuvring tests were realised. Model obtained from DST Duisburg Germany was a 5.00 meters long motor barge built to a scale of 1:20 and propelled with an 80 mm diameter ducted propeller. Tests were carried out in the auxiliary towing tank of the Ship Hydromechanics Division in Gdańsk. The experiment consisted of efficiency analysis of different rudder blades with variable rudder profiles and rudder blade areas. In total the evasive action test was repeated for three different rudder profiles, with three different chord lengths and at three different water depths each. For each particular case the total standard manoeuvre time and side rudder force was measured. These results were compared with the RheinSchUO standards. The model tests programme was realised within the EU CREATING project supported in the 6th Framework Programme
Breeding season timing and breeding success of Tufted Duck were studied on three lakes in the years 1987-1989. Clutch laying began in mid May, earliest in a Black-headed Gull colony, and continued to the first days of July. Clutch size ranged between 3 and 18 eggs ( x = 9.3, SD = 2.8, n = 331) and did not differ significantly between lakes and years. There was a significant reduction in clutch size as the nesting season advanced (from 13.3 eggs in May to 6.3 in July). Nesting losses (25-90% failed nests or clutches) grew as the breeding season progressed. Ducklings came to the water beetween the end of June and the beginning of August. Duckling losses (20-90%) were inversely correlated with nesting failures and due mainly to predation. The investigated populations were characterized by very limited production of young in most lakes and seasons and, as a consequence, by a decline in the population to half that noted in the 1970s.
Artykuł dotyczy zagadnień bezpieczeństwa i trwałości budynków wzniesionych w technologiach wielkopłytowych w latach 1960–1990. W tym okresie na różnych etapach procesu inwestycyjnego dochodziło do wielu nieprawidłowości, które mogły skutkować obniżeniem jakości wykonawstwa budynków i powstawaniem wielu różnych defektów m.in. w obszarze złączy konstrukcyjnych między elementami prefabrykowanymi. W artykule wskazano możliwość wykorzystania modelowania numerycznego do oceny pracy połączeń, w których występuje np. niejednorodność struktury materiału wypełniającego (tzw. raki). Do analiz wybrano poziome złącza stropu i wewnętrznej ściany nośnej wykonane w systemie centralnym Wk-70. W pracy przedstawiono wyniki wariantowych symulacji komputerowych pracy tzw. złącza referencyjnego oraz złączy zawierających zmienny udział, rozmieszczenie i kształt defektów. Wyniki obliczeń mogą stanowić podstawę do wskazania kierunków prac diagnostycznych budynków wielkopłytowych, oceny stanu technicznego konstrukcji i podjęcia decyzji o jej naprawie lub wzmocnieniu.
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