Wyniki wyszukiwania - BazTech

1

Wybrane zagadnienia projektowania sonotrod na potrzeby obróbki ubytkowej wspomaganej drganiami ultradźwiękowymi obrabianego przedmiotu

Krok M., Porzycki J., Żółkoś K.

Mechanik

|

2016

|

R. 89, nr 10

1354--1355

PL

W artykule przedstawiono wybrane zagadnienia związane z projektowaniem sonotrod na potrzeby obróbek ubytkowych, takich jak frezowanie czy szlifowanie, gdzie w ruch drgający wprowadzany jest przedmiot obrabiany. Omówiono materiały stosowane na sonotrody, obciążenia mechaniczne przedmiotu obrabianego oraz charakterystykę pracy falowodu.

EN

The article presents selected issues related to the design sonotrodes for the needs of machining processes such as milling and grinding, wherein the oscillatory motion is inducted into the workpiece. The materials used for the purpose of ultrasonic vibrations, mechanical loads of the workpiece and the operating characteristics of the waveguide are described.

2

Does the Magpie Pica pica (L.) prefer poplars as a nesting tree in the urban environment?

Meissner W., Żółkoś K.

Polish Journal of Ecology

|

2010

|

Vol. 58, nr 2

371-377

EN

This paper aims to verify the hypothesis that magpies in urban environments favour poplars as nesting trees, as suggested by previous authors. The fieldwork was conducted in a 180 ha area in a district of Gdańsk (North Poland). The study area held 5294 trees and high shrubs, where 124 magpie nests were found in 10 species of trees. Results of log-linear analysis showed that the magpies chose particular tree species rather than types of spatial tree organization. The lombardy poplar (Populus nigra "Italica") is the species most frequently chosen as a nest tree, however - the magpies showed a significant preference for trees growing separately or in pairs. The choice index (the ratio of expected to observed frequency) confirmed the magpies. strong preference for black poplar cultivars and for birches, regardless of the trees. grouping. The magpies preferred lombardy poplar when they had the choice of two poplar cultivars. This cultivar has a crown suitable for the magpie's nest construction because of the small angle between the trunk and the branches. The thin, almost vertical branches probably also limit predators from penetrating the crown because these branches do not provide much support for tree climbers. The large-scale planting of lombardy poplars in Polish towns in the 1960s and 1970s has probably contributed to the significant increase of the magpie population in the urban environment.

3

The effect of Grey Heron (Ardea cinerea L.) colony on the surrounding vegetation and the biometrical features of three undergrowth species

Żółkoś K., Meissner W.

Polish Journal of Ecology

|

2008

|

Vol. 56, nr 1

65-74

EN

Bird breeding colonies are known to influence the habitats and phytocoenoses they occupy in different ways. Most papers concern long-lasting colonies, in which floristic composition of phytocoenoses have been already altered largely. This research was aimed to estimate the changes in the floristic composition of the forest phytocoenosis after three years of the existence of the Grey Heron (Ardea cinerea L.) breeding colony as well as to examine the influence of nutrient enrichment on the size and shape of leaves and inflorescences of three plant species Rumex acetosella L., Anthoxanthum odoratum L. and Moehringia trinervia (L.) Clairv., which have different habitat requirements. The number of vascular plant species within the colony area (0.4 ha) increased almost double and appearance of new, mostly nitrophilous, taxa like Sambucus racemosa L., Galeopsis pubescens Besser and Stellana media (L.) Vill. were observed. The vertical structure of phytocoenosis has also changed. The undergrowth appeared and dense moss layer was mostly eliminated. In case of all investigated species, the enlargement of leaf surface was found. The greatest relative increase concerned leaf width of Moehringia trinervia and Rumex acetosella - 67 and 73%, respectively. The leaf blade of Anthoxanthum odoratum increased largely in length (99%). The enlargement of the surface of assimilative apparatus was not only due to the increase of linear dimensions, but also to rounding of the leaf blade. This was not observed in case of Rumex acetosella which is characterized by elongated, lanceolate leaf blade. Differences observed among the species are probably due to differentiated leaf blade structure. Only Moehringia trinervia can be found in well-established Grey Heron colonies, while Rumex acetosella and Anthoxanthum odoratum are known to be suppressed by heavy input of nitrogen fertilizer. Thus, it seems that after few years of benefits at least Rumex acetosella and Anthoxanthum odoratum withdraw from the area altered by Grey Heron colony, because the change in root absorption and capacity in highly fertile habitat leads to toxic accumulation of nutrients.