CLASSIFICATION AND MODELLING OF SOUND EMISSION SIGNALS IN SELECTED TRIBOSYSTEMS

The paper presents an analysis of the sound level recorded during dry sliding friction conditions. Balls with a diameter of 6 mm placed on pins were made of 100Cr6 steel, silicon carbide (SiC), and corundum (Al2O3), while rotating discs with a height of 6 mm and a diameter of 42 mm were made of 100Cr6 steel. Each pin and disc system was tested for two values of the relative humidity of the air (50 ± 5% and 90 ± 5%). Models of the A-sound level were developed using regression trees and random forest. The paper presents an analysis of the accuracy of the models obtained. Classifications of the six tests performed on the basis of sound level descriptors were also carried out.

Analysis of the Particles’ Movement Over the Flat and Profiled Rotating Discs surface in the Velocity Layer of the Viscous Gas

Experiments on the rotating in the air cones with vertex angle β = 120º and flat disc shown that on frequencies Ω ≥ 2.5 hertz exists a qualitative difference in movement for the particles with diameters d ≈ 1 mm and d ≈ 0.1 mm. The particles with d ≈ 0.1 mm move in the near-surface region, the particles with d ≈ 1 mm jump up to 3 cm. Comparison of the spherical and aspheric (ellipsoid with axles d, d and 4 /3 d) particles' kinematics moving shown the inevitability of the large particles jump occurrence. Large particles come to self-oscillation regime by reason of periodically appearance of the Magnus force. Small particles are localized in the velocity layer

Wear of a rough disc in dry sliding contact with a smooth ball: experiment and modeling

The main objective of this work is to model wear of a disc which was subjected to dry contact with a ball in unidirectional sliding. Tribological tests of sliding pairs were carried out using a tribological tester T-11 in a ball-on disc configuration. Stationary balls made of 100Cr6 steel with a hardness of 62 ± 2 HRC co-acted with rotating discs with 42CrMo4 steel with a hardness of 40 ± 2HRC. Discs were machined by lapping, grinding, milling, and vapour blasting. The values of the Sq parameter of disc surfaces were between 0.1 and 5.86 µm. Wear volumes of the discs were lower for bigger roughness heights. The simulation of disc wear was conducted on the basis of the repetitive contact between sliding surfaces. Strong correlation was achieved between the modeled and measured volumetric wear levels.

The First 3D Movies

3-D movies have gone through several waves of popularity. They have appeared several times in the 20th and 21st centuries, with new developments in technology enabling better effects with each new incarnation. Rotating discs, polarizing glasses, anaglyphic glasses, coupled polarizers and optical retarders, and the use of electro-optic shutters each provided small advantages over previous technology. But the basic idea is simple, and was used in the 19th century stereoscope—present each eye with an independent view from a different perspective so that the parallax enables the brain to fuse them into one stereoscopic image. Who invented the first 3D movies? The idea is much older than most people suspect, dating back to the very beginning of cinema.

Using angular momentum maps to detect kinematically distinct galactic components

ABSTRACT In this work, we introduce a physically motivated method of performing disc/spheroid decomposition of simulated galaxies, which we apply to the eagle sample. We make use of the healpix package to create Mollweide projections of the angular momentum map of each galaxy’s stellar particles. A number of features arise on the angular momentum space which allows us to decompose galaxies and classify them into different morphological types. We assign stellar particles with angular separation of less/greater than 30° from the densest grid cell on the angular momentum sphere to the disc/spheroid components, respectively. We analyse the spatial distribution for a subsample of galaxies and show that the surface density profiles of the disc and spheroid closely follow an exponential and a Sérsic profile, respectively. In addition discs rotate faster, have smaller velocity dispersions, are younger and are more metal rich than spheroids. Thus, our morphological classification reproduces the observed properties of such systems. Finally, we demonstrate that our method is able to identify a significant population of galaxies with counter-rotating discs and provide a more realistic classification of such systems compared to previous methods.