Braham Prakash

A systematic methodology to characterise the running-in and steady-state wear processes

An improved methodology has been developed to characterise running-in and steady-state wear processes. The experimental study was conducted with En 31 steel specimens on reciprocating tester with ball-on-flat geometry under lubricated sliding conditions. The tests were conducted according to a factorial design. The variables selected were the load, temperature and surface roughness. The wear behaviour for a given set of operating conditions has been characterised on the basis of developed methodology. The parametric influence of operating conditions was then analysed on the basis of polynomial relationships. The steady-state wear was found to be significantly influenced by the initial roughness.

Assessment of engine liner wear from bearing area curves

Abstract This paper proposes a new procedure to evaluate engine liner wear volume and wear depth particularly for short duration engine tests. The method is based on the fact that honing depth is not removed when small amount of wear occurs. It was considered that 90% point of the bearing area curve is the same before and after wear. Then, the bearing area curve for the used liner was transformed by the depth differences at 90% and the area between the two curves was calculated by numerical procedure. As the diameter of the liner is known, the wear volume was calculated for the various zones selected at different points from TDC and BDC. The methodology involved has been programmed in C++. The wear depth is obtained by the projection on the depth axis of the two bearing area curves, and then finding their difference. This method is considered superior to the usual method of gauging the changes in diameter as such determinations are influenced by the distortions that occur in the liner. The new procedure needs to be applied more extensively to improve confidence in repeatability and reproducibility and to determine the limits of applicability. Controlled laboratory wear tests and further measurements on cylinders from field engines are therefore proposed.

Contact Pressure Dependency in Frictional Behavior of Burnished Molybdenum Disulphide Coatings

The drop of coefficient of friction of MoS2 coatings with increase in contact pressure has been reported by various earlier researchers. Different hypothesis have been put forward to explain this phenomenon. This paper covers details of experiments carried out to investigate this further. Experiments have been carried out on reciprocating sliding wear and friction machine to bring out the influence of different parameters on the tribological behavior of MoS2 films. Role of frictional heating in this behavior has also been brought out. It is concluded that frictional properties of MoS2 are dependent on prevalent humidity as well as contact pressure and the drop of μ with contact pressure is independent of frictional heating.

A sensitive assay for ornithine amino transferase in rat brain mitochondria by ninhydrin method.

To establish/develop an assay method for measuring Ornithine Aminotransferase (EC.2.6.1.13) activity using rat brain mitochondria as a source of enzyme in presence and absence of Pyridoxal Phosphate (PLP). The modified method, with the improved sensitivity, is adopted for the assay of ornithine amino transferase activity in rat brain mitochondria. The enzyme activity was measured at 620 nm, the study showed that reaction was optimum at 37°C for 30 minutes. The assay is sensitive enough to detect activity at the order of nanomoles pyrroline-5-carboxylate/mg protein/minute and can be compared as an alternative to the radio isotopic method which is more cumbersome and aminobenzaldehyde method which is less sensitive. The Km & Vmax shows maximum activity in the presence of Pyridoxal Phosphate (Coenzyme) concentration at 0.05mM when compared with absence of Pyridoxal Phosphate as higher the concentration of Pyridoxal Phosphate affects the affinity of the enzyme to substrate. The OAT activity in different tissues of the rat was also studied and highest activity was found in liver and kidney.

Characterization and Evaluation of Hill Cattle of Garhwal Region of Uttarakhand, India

A survey was conducted in 18 villages of Rudarpryag, Chamoli and Uttarkashi districts of Garhwal region to characterize hill cattle in the region. A total of 146 farmers and 451 animals of different age and sex were covered in the present study. The survey revealed that there is large number of hill cattle in the region. Animals of were reared on semi intensive system of management. Grazing was from afternoon to evening during the whole year. Animals were smaller in size with cylindrical type of body. The black body colour predominates in the region. Udder was small, touching to the body, not well developed and milk veins were not prominent. Sizes of fore and rear udder were small. The ranges of different biometric traits showed that animals are similar to Vechur and Panganaur for their size and smaller than the Hariana and Sahiwal breeds of cattle. The average age at first calving, daily milk yield, lactation length, dry period, service period and calving interval were 42 months, 1.52 kg, 285 days, 120 days, 110 days and 364 days, respectively. A pair of bullock may plough about 4-6 Nali of land in 3 to 4 hours in a day. A total of 51 blood samples of unrelated hill cattle animals were collected from Garhwal region for genetic characterization. DNA was isolated and analyzed by a panel of 21 microsatellite markers.The average observed and expected number of alleles, observed and expected heterozygocity and heterozygote deficit were 12.91 (6-12), 5.66 (2.41 to 11.39), 0.699 (0.271 to 0.938), 0.782 (0.585 to 0.912) and 0.118 ( -0.198 to 0.537), respectively. The different genetic diversity parameters showed that population is comparable with the hill cattle of Kumanu region and Hariana cattle. Different parameters showed sufficient allelic diversity in the population