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The present work includes the study of boundary lubrication properties of SAE20W40 lubricating oil added with aluminum oxide nanoparticles. Pin-on-disk tribometer is employed to study the effects of nanoparticles in different sizes (40–80 nm) and concentrations (0–1% by weight) on the friction coefficient. The experimental design consists of L18 orthogonal array involving six levels for nanoparticles concentration and three levels for nanoparticles size, sliding speed, and normal load. The presence of nanoparticles has significantly improved the lubrication properties of oil. Minimum friction coefficient is recorded at 1200 rpm rotational speed and 160 N normal load for 0.8% concentration of 60 nm sized nanoparticles. Scanning electron microscopy (SEM) and electron diffraction spectrometry (XRD) are employed to understand the friction reduction mechanism.

In general, the splitting operation on a binary matroid M does not preserve the connectivity of M. In this paper, we provide sufficient conditions to preserve n-connectedness of a binary matroid under splitting operation. As a consequence, for an (n + 1)connected binary matroid M, we give a precise characterization of when the splitting matroid M T is n-connected. c

Slater introduced the point-addition operation on graphs to characterize 4-connected graphs. The Γ-extension operation on binary matroids is a generalization of the point-addition operation. In general, under the Γ-extension operation the properties like graphicness and cographicness of matroids are not preserved. In this paper, we obtain forbidden minor characterizations for binary matroids whose Γ-extension matroids are graphic (respectively, cographic).

Zaslavsky introduced the concept of lifted-graphic matroid. For binary matroids, a binary elementary lift can be defined in terms of the splitting operation. In this paper, we give a method to get a forbidden-minor characterization for the class of graphic matroids whose all lifted-graphic matroids are also graphic using the splitting operation.