Discharge water quality from old ditch networks in Finnish peatland forests

Tiivistelmä: Vanhoilta metsäojitusalueilta valuvan veden ominaisuudet

Old age from antiquity to post modernity

Teksti suomeksi

Stem straightness and compression wood in a 22-year-old stand of container-grown Scots pine trees

Abstract

Age and size structure of gap-dynamic, old-growth boreal forest stands in Newfoundland

[Abstract]

Structure of old Pinus sylvestris dominated forest stands along a geographic and human impact gradient in mid-boreal Fennoscandia

Abstract

Australiassa muistitietotutkimus on "must" : Old Stories, New Ways

Ajankohtaista

Effects of modern variable frequency drive on the reliability of an old crane induction motor

The work aims to analyze the possibilities of utilizing old crane driving AC induction motors in modern pulse-width-modulated variable frequency drives. Bearing currents and voltage stresses are the two main problems associated with modern IGBT inverters, and they may cause premature failure of an old induction motor. The origins of these two problems are studied. An analysis of the mechanism of bearing failure is proposed. Certain types of bearing currents are considered in detail. The most effective and economical means are chosen for bearing currents mitigation. Transient phenomena of cables and mechanism of over voltages occurring at motor terminals are studied in the work. The weakest places of the stator winding insulation system are shown and recommendations are given considering the mitigation of voltage stresses. Only the most appropriate and cost effective preventative methods are chosen for old motor drives. Rewinding of old motors is also considered.

Symphony no. 4 in A, op. 90 "Italian"

Taltioitu radioidusta esityksestä 28.2.1954.