Wyniki wyszukiwania - BazTech

1

Commutators of diffeomorphisms of a manifold with corners

Lech J.

Demonstratio Mathematica

|

2007

|

Vol. 40, nr 2

465-480

EN

It is shown that the identity component of the group of al compac tly suported C infinity -diffeomorphisms of a manifold with corners is perfect provided the manifold has no vertices. An analogous result for Cr -diffeomorphism still holds whenever r > n+1, wheren is the dimension of the manifold. These results constiute a generalization of a well-known theorem by Thurston and Mather on the simplicity of diffeomorphism groups of boundaryless manifolds.

2

Komputerowe wspomaganie nauczania z zakresu komutatorów

Strzęciwilk D.

Studia Informatica

|

2005

|

Vol. 26, nr 2

81-92

PL

W artykule przedstawiono przykład rozwiązania systemu wspomagającego nauczanie z zakresu komutatorów. Zaprezentowano możliwości systemu dydaktycznego umożliwiającego wszechstronne ćwiczenia w ramach tematyki multiplekserów i demultiplekserów. Omówiono również możliwości systemu wspomagającego nauczanie z zakresu zagadnień komutatorów do realizacji funkcji logicznych.

EN

The article describes an example of a solution for system aided teaching of commutators. Possibilities and versatility of exercises of didactic program used for teaching of multiplexers and demultiplexers have been presented. Possibilities of didactic system for teaching of commutators in realizations of logical functions were presented too.

3

Badanie stanu powierzchni komutatora silnika maszyny wyciągowej

Antal L., Zawilak J.

Maszyny Elektryczne : zeszyty problemowe

|

2002

|

Nr 64

75-80

EN

A strong sparking between brushes and commutator had occured in one of four motors, driving a shaft hoist in the copper mine, and that caused some burnings of the commutator segments surface. The burnings zones were of regular pattern, repeating 16 times along the commutator circumference of 16-pole machine (fig. 1). It has been established, that the most probable cause of the sparking is an invisible damage of the commutator surface. A state of commutator surface was examined by supplying, from an external source, the insulated brushes with an electric current of constant value and recording the brush voltage and current variations, speed and impulses signaling the commutator. Measuring signals were recorded with tape recorder at sampling frequency of 24 kHz. The motor was driven by another identical D.C. motor. Testing was done for both directions of rotation and for different positions of the testing brushes in the brush holder. The tests were made three times for different states of the commutator surface. It was found that there were big voltage impulses induced at some commutator segments, which indicated instantaneous interruption of the current circuit. On this basis, a repair of the commutator was recommended. All fixing screws were tighten and the commutator surface was turned. The repair proved effective and the negative phenomena disappeared.

4

Zjawiska występujące w komutatorach maszyn małej mocy w stanie dynamicznym

Wylężek E.

Maszyny Elektryczne : zeszyty problemowe

|

2000

|

Nr 61

257-260

PL

W artykule przedstawiono problemy i zjawiska występujące w komutatorach maszyn wysokoobrotowych małej mocy w trakcie ich pracy przy różnych prędkościach obrotowych - w tzw. stanie dynamicznym. Przedstawiono oscylogramy stanu powierzchni komutatora - odkształcenia dynamiczne w czasie pracy maszyn oraz przyczyny ich powstawania.