The Analysis of the Characteristics of Infinitely Short Journal Bearings Modified by Equivalent Viscosity
The characteristics of unlimited short journal bearing has been analyzed by using the equivalent viscosity correction model under thin film lubrication conditions. The interaction between the lubricant and the surface within a very small gap has been seriously considered. The changes of regular pattern of lubricant properties are comprehensive analyzed and researched. Unlimited short journal bearing is regarded as the research object. After researching, the varying regularity of its characteristics has been received. At the same time, the relationship between parameters and bearing performance has been established. The basis are provided for theoretical research and practical engineering calculations.
PROGRESS OF RESEARCH ON NANOTRIBOLOGY
With the development of nano science and technol- ogy,nanotribology has been a fundamental technology involved in super precise machine and micro electromechanical systems, which focus on the atom/molecule-scale friction,lubrication and wear properties of tribological interfaces.Since early 1990s, Chinese tribologists have devoted themselves into this field and made remarkable achievements.The main research progress on nanotribology from the State Key Laboratory of Tribology, Tsinghua University is summarized,including thin film lubrica- tion,confined liquid properties,ordered molecular film lubrica- tion,interface friction and stick-slip phenomena,magnetic head/disk nanotribology and the development of experimental instruments,etc.To serve as a valuable reference for future study is expected in nanotribology.
Identification of Dihydroxy Aromatic Compounds in a Low-Temperature Pyrolysis Coal Tar by Gas Chromatography−Mass Spectrometry (GC−MS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)
Dihydroxy aromatics in coal tar undergo rapid coupling reactions with each other and with some coal-derived species during coal pyrolysis and liquefaction. However, only limited information on the structure of dihydroxy aromatics is known. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography−mass spectrometry (GC−MS) were used to characterize the dihydroxy aromatics in a low-temperature pyrolyzed coal tar and its distillate and residue fractions. Negative-ion electrospray ionization (ESI) FT-ICR MS spectra of coal-tar-derived samples had low molecular masses and narrow mass ranges. Negative-ion ESI is extremely selective for the dihydroxy aromatics present in coal tar. The O2 class species had the highest ion intensity among the species in the negative-ion FT-ICR mass spectrum for each sample. Dihydroxy compounds with an aromatic core structure of benzene, indan, biphenyl (and/or acenaphthene), and naphthalene were identified in the distillate fract...