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This paper deals with the analysis of the influence of base oil viscosity on the ability of ZDDP-containing lubricants to form protective layers (especially antiwear layers). The chemical structure of additives used was characterised according to their thermal stability, determined by differential scanning calorimetry (DSC). The additives were added to base oils of various viscosities. The prepared lubricants were tested using a four-ball machine, and analysed by DSC. The relationships between base oil viscosity and seizure load (Pt), weld load (Pw) and DSC test results are presented and discussed. The mechanism of interaction between ZDDP and the base oils was analysed by the use of a mathematical model. 相似文献
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Scientometrics - This country case study describes how science policy instruments are designed to shape publication patterns and identifies the changes in researchers’ productivity that can... 相似文献
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This paper presents an assessment of tribological properties of compositions of fuel oil containing fatty acid methyl esters derived from rape-seed oil. An HFRR (high-frequency reciprocating rig – ball-on-flat) apparatus was used in this investigation. The studies were carried out for a steel–steel pair in the concentrated contact.The tribological properties were determined by motion resistances, wear and lubricant film concentration. The surfaces were analysed after tribological tests. The aim of the investigation was an attempt to obtain a correlation between wear quantities being measured and percentage content of bioadditives in fuel oil. It was found that at as little as 5% of the additive the coefficient of friction decreases by about 20% while wear decreases twofold relative to fuel oil, which may result from an increase in the stability of the lubricant film. 相似文献
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Andrzej Kulczycki 《Wear》1985,103(1):67-75
A general method for anticipating results of highly complex tests on the basis of simple measurements has not yet been worked out. An energy-based method for determining antiwear and extreme pressure (EP) properties of oils containing additives is described in the present paper. The method allows the parameters characterizing the ability of additive-containing oils to form boundary layers in the antiwear (αAW) and EP (αEP) regions to be determined.The parameters αAW and αEP make it possible to correlate the results of different friction tests. The correlation between seizure load Pt, welding load Pz, wear load index Ih, four-ball wear test results d40 and results of the FZG tests is presented in this paper. 相似文献
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Scientometrics - In this study, we investigate what share of researchers publish monographs across fields, gender and seniority. We acquired data from the Polish current research information system... 相似文献
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This note describes a systematic procedure for the control synthesis of a rigid spacecraft using the energy shaping method. The geometric concept of a mechanical system in a coordinate-independent form is used to derive a control algorithm for the Euler-Poincare equations. The main result of this note is a specialization of the method on the unit quaternion group. This note is concluded with the examples of the potential functions and implementation for the three-axis attitude control problem. 相似文献
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Jorge Buescu Marcin Kulczycki Ian Stewart 《Dynamical Systems: An International Journal》2006,21(3):379-384
We give a revised proof of a theorem originally due to Buescu and Stewart (1995). The new version of this theorem dispenses with the assumption that the space X is locally compact. The theorem is as follows: let X be a locally connected metric space, let f,:,X→X be a continuous map, and let A⊂X be a Liapunov stable compact transitive set that has infinitely many connected components. Then the map induced by f on the space of connected components of A is topologically conjugate to an adding machine. 相似文献
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Kulczycki Emanuel Engels Tim C. E. Pölönen Janne Bruun Kasper Dušková Marta Guns Raf Nowotniak Robert Petr Michal Sivertsen Gunnar Istenič Starčič Andreja Zuccala Alesia 《Scientometrics》2018,115(1):463-486
Scientometrics - The increasing number of open-access full-text scientific documents promotes the transformation from metadata- to content-based studies, which is more detailed and semantic. Along... 相似文献
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Kowal Marta Sorokowski Piotr Kulczycki Emanuel Żelaźniewicz Agnieszka 《Scientometrics》2022,127(1):265-273
Scientometrics - The beauty of science lies within its core assumption that it seeks to identify the truth, and as such, the truth stands alone and does not depend on the person who proclaims it.... 相似文献