This paper demonstrates the applications of artificial neural networks to predict the equivalent continuous sound level (L Aeq ) and 10 Percentile exceeded sound level (L 10 ) generated due to traffic noise for various locations in Delhi. A Model based on back-propagation neural network was trained, validated, and tested using the measured data. The work shows that the model is able to produce accurate predictions of hourly traffic noise levels. A comparative study shows that neural networks out-perform the multiple linear regression models developed in terms of total traffic flow and equivalent traffic flow. The prediction model proposed in the study may serve as a vital tool for traffic noise forecasting and noise abatement measures to be undertaken for Delhi city.

A mathematical model is developed to analyse the effect of polymer additives on thermal elastohydrodynamic lubrication (EHL) behaviour under heavily-loaded rolling/sliding line contacts. The lubricant is assumed to be couple stress fluid and a non-dimensional couple stress parameter represents the molecular length of the additives. The Reynolds and mean temperature equations for the couple stress fluid (CSF) are derived using the rheological relationship presented by Stokes. The thermal EHL characteristics computed for polymer modified oils are found to have a strong dependence on the couple stress parameter. Polymer additives are shown to cause a significant increase in fluid-film thickness along with a noteworthy reduction in the coefficient of friction without any rise in fluid pressure. In addition, the polymer additives are found to cause a minimization of the thermal reduction in the fluid-film thickness as a well as decrease in fluid temperature, particularly under low speed-high load conditions, where fluid films are quite thin. These improvements are desirable in situations involving continuously varying slide to roll ratios, e.g. in gears.

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The effect of couple stress fluids on elastohydrodynamic lubrication (EHL) behaviour in smooth as well as rough line contacts is investigated numerically at low speed-high load and high speed-low load conditions. A non-dimensional couple stress parameter represents the molecular length of the additives. The EHL characteristics computed for couple stress fluids are found to have strong dependence on couple stress parameter. Significant increase in minimum film thickness due to couple stress fluid is observed. Also, the surface roughness effects on EHL behaviour are influenced by couple stress fluid to an extent depending upon the speed-load conditions.

A complete numerical solution to the transient elastohydrodynamic lubrication (EHL) problem of an involute spur gear is obtained under isothermal condition. The lubricant is assumed to be couple-stress fluid and the transient Reynolds equation for the compressible couple-stress fluid is derived using Stokes theory. The EHL characteristics computed for couple-stress fluids are found to have strong dependence on couple-stress parameter. Significant increase in minimum film thickness due to couple-stress fluid is observed. Also, it is found that couple-stress fluids tend to smoothen the variation of film thickness along the line of action caused by transient effects.

A theoretical analysis on Belleville spring with parabolically varying thickness is presented in this study. The analysis aims at modifying the thickness profile of radially tapered Belleville spring in order to increase the span of null slope zone in its stiffness curve, which is beneficial in some regulation processes. The expression for linearly varying thickness used by Rosa et al. is modified to incorporate a curvature factor and the corresponding load as well as stress equations are derived using the hypothesis of Almen -Laszlo. On the basis of this analysis, it is found that a spring with convex parabolic thickness profile serves better than an equally tapered spring with linear profile in regulation processes.

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A theoretical investigation has been undertaken to study operating temperatures, heat fluxes and radial thermal stresses in the valves of a modern diesel engine with and without air-cavity. Temperatures, heat fluxes and radial thermal stresses were measured theoretically for both cases under all four thermal loading conditions. By creating an air cavity inside the valves stem, it acts as an insulating medium and prevents the heat flow, hence the need of providing insulation coating on valves is minimized. The main motive of this is to reduce the weight of engine and cost associated with thermal coating. Results observed in the engine valves revealed that after creating an optimized air cavity in the valve, thermal stresses and temperatures at all nodal points decreases slightly. The weight of the valve decreased up to 11% without losing its strength. In addition to heat transferred by convection and radiation from combustion gases, the temperature and heat flux distributions are considerably affected by heat conduction from valve seat. The temperature field, heat transfer rate and thermal stresses were investigated with numerical simulation models using FORTRAN FE (finite element) software.