Inexpensive high‐precision system for measuring air pressure fluctuations

The work is devoted to the development of integrated thermostating subsystem of a high-precision system for measuring the thickness of hot metal rolling. The developed thermostatting subsystem includes active and passive modules, which ensured thermostability of the measuring modules at the level of 0.5 degrees in a hot metallurgical workshop. Thermal stabilization made it possible to ensure high accuracy in measuring the thickness of hot metal rolling in a hot metallurgical production workshop.

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Chaotic air pressure fluctuations during departure of air bubbles from two neighbouring nozzles

Archives of Thermodynamics ◽

10.2478/v10173-012-0006-z ◽

2012 ◽

Vol 33 (1) ◽

pp. 127-137 ◽

Cited By ~ 1

Author(s):

Romuald Mosdorf ◽

Tomasz Wyszkowski

Keyword(s):

Correlation Dimension ◽

Cross Correlation ◽

Pressure Fluctuations ◽

Air Pressure ◽

Hydrodynamic Interactions ◽

Largest Lyapunov Exponent ◽

Distilled Water ◽

Air Bubbles ◽

Bubble Interactions ◽

Correlation Exponent

Chaotic air pressure fluctuations during departure of air bubbles from two neighbouring nozzlesIn the experiment, bubbles were generated from two brass nozzles with inner diameters of 1.1 mm. They were submerged in the glass tank filled with distilled water. There have been measured the air pressure fluctuations and the signal from the laser-phototransistor sensor. For analysis of the pressure signal the correlation (the normalized cross - correlation exponent) and non-linear analyses have been used. It has been shown that hydrodynamic interactions between bubbles can lead to bubble departure synchronization. In this case the bubble departures become periodic. The results of calculation of correlation dimension and the largest Lyapunov exponent confirm that hydrodynamic bubble interactions observed for 4 mm spacing between nozzels cause the periodic bubble departures from two neighbouring nozzles.

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Air bearings in high precision systems

International Journal Sustainable Construction & Design ◽

10.21825/scad.v4i2.1041 ◽

2014 ◽

Vol 4 (2) ◽

Author(s):

I. Cracaoanu ◽

F. Bremer

Keyword(s):

Surface Topography ◽

High Precision ◽

Air Bearing ◽

Test Results ◽

Air Bearings ◽

Bearing Surface ◽

Operational Parameters ◽

Low Friction ◽

Air Supply ◽

Precision System

In high precision system applications low friction levels between components are desirable. Moving heavy parts at high speeds and accelerations without friction is possible by using air bearings. The main failure ofthe air bearings is the wear phenomenon (modification of surface topography) that occurs due to crash into the counterpart when air supply is interrupted. The aim of this research is to investigate different types of air bearings for a large number of crashes using real operational parameters from the field: speed, acceleration, load and supply air pressure. The real crash phenomenon in a high precision machine hasbeen replicated using a test setup. During testing, evolution of air bearing surface topography and air bearing characteristics (gap and flow) after different number of crashes are investigated. Test results showthat some air bearings are not reaching the specified number of crashes due to large defects that occur on the bearing surface. Some specific relations were found between crash defects and parameters such asthe air gap size and the direct contact between opposing surfaces. The preferred type of air bearings shows good performance even above the maximum specified number of crashes. This behavior can be explainedby low friction level during crash tests between the opposing surfaces. The test results from this investigation produced a reliable candidate for air bearings in the high precision system application.

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