2,454 research outputs found
Abrasion resistance of selected commercially available polymer materials
The aim of this investigation was to examine several types of commercially available polymers for potential application in machine elements that are exposed to abrasion. Selected materials were evaluated on a rubber and steel wheel abrasion test rig according to the standard ASTM G65, using as abrasive quartz sand (SiO2) as abrasive, with a particle grain size in the range of 0.8 – 1.6 mm. Tests were performed under dry conditions and at room temperature. Applied load was 50 N, within testing times of 1½, 3, 4½, and 6 hours respectively. Results of testing revealed influence on wear behavior of polymer hardness as well as influence of abrasive particle embedment
k-Dirac operator and parabolic geometries
The principal group of a Klein geometry has canonical left action on the
homogeneous space of the geometry and this action induces action on the spaces
of sections of vector bundles over the homogeneous space. This paper is about
construction of differential operators invariant with respect to the induced
action of the principal group of a particular type of parabolic geometry. These
operators form sequences which are related to the minimal resolutions of the
k-Dirac operators studied in Clifford analysis
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