MRT letter: Real time and in situ imaging the reversible evolution of ethanol vapor condensed on mica surface

The reversible adsorption and desorption of ethanol vapor on mica surface at ambient temperature were investigated in situ with time-evolution by Vibrating Scanning Polarization Force Microscopy (VSPFM). At temperature 20 °C and relative humidity 20%, ethanol vapor condensed and formed clusters on the freshly cleaved mica. These clusters expanded to a network structure and later formed a full film shown by continuous VSPFM imaging. The film broke into pieces and desorbed completely if in unsaturated condition. The film showed different apparent heights when different biases were used in VSPFM study, indicated polarized orientation of the ethanol molecules on the mica surface. It is a process of hours for the clusters or network structures to form a film on mica, which demonstrated that vapor ethanol molecule is not so easy to precipitate on mica as ethanol molecule in liquid stage.     

A novel test rig for in situ and real time optical measurement of the contact area evolution during pre-sliding of a spherical contact

An experimental test rig was developed in order to investigate elastic–plastic single micro-spherical contact under combined normal and tangential loading. This novel apparatus allows in situ and real time direct optical measurement of the real contact area (RCA) evolution in pre-sliding. It also allows relative displacement measurements under very low rates of tangential loading (down to 0.01 N/s) to capture accurately the fine details at sliding inception. This is achieved by piezoelectric actuation in closed loop feedback control in addition to synchronization with data and image acquisition to obtain real time measurement. The RCA measurement is realized by direct optical observation technique, whereas two different image processing algorithms were implemented for the elastic and the elastic–plastic contact regimes. The various features and capabilities of the test rig are presented along with some preliminary experimental results of RCA and friction behavior to assess its performance.     

Effects of oil inlet pressure and inlet position of axially grooved infinitely long journal bearings. Part I: Analytical solutions and static performance

This paper presents analytical expressions for the dynamic pressure and dynamic fluid force in axially grooved long journal bearings with consideration of oil inlet pressure and inlet position. The effects of oil inlet pressure (in the range of , where the dimensionless oil inlet pressure ) and oil inlet position (in the range of 0Θ_i90°) on the static oil film configuration, pressure distribution, and steady state journal position in axially grooved journal bearings are discussed. In this paper, Reynolds–Floberg–Jakobsson boundary conditions are assumed to account for the appropriate starting position of the cavitation, the reformation of oil film at the end of caviation, and the effect of oil inlet pressure and inlet position.