This paper deals with the modeling of a vertically coupled vehicle-slab track using finite element method. The slab track system is represented by a two layer Euler-Bernoulli beam model including rail and concrete slab. The vertical stiffness of track bed is assumed to be random variable using Monte Carlo simulation. The vehicle is simplified as a multi-body system with 10 degrees of freedom. The accuracy of the simulation is verified by deterministic and random approaches as well. Sensitivity analyses on the various parameters such as slab thickness, coefficient of track bed stiffness, vehicle velocity are performed. It is demonstrated that the uncertainty in track bed stiffness has a major effect on rail and slab deflections. From a practical point of view, the obtained results of the present study can be utilized efficiently in the analysis and design of slab track systems.

The main design criteria of ballasted railway tracks include rail deflections, rail bending stresses, rail wheel contact stresses, sleeper bending moments and ballast sleeper contact pressures. Various criteria have been defined for the design of ballasted railway tracks due to the various mechanical properties of track components and their complex interaction. Therefore, the railway track design is a difficult and time-consuming process. These complications highlight the need to focus attention on the necessity of a thorough investigation into the effect of the track and rolling stock parameters on the design criteria. In an attempt to overcome this problem, a sensitivity analysis of the main railway track design criteria was conducted in this study. Consequently, the roles of track and rolling stock parameters (including track modulus, sleeper spacing, train speed and axle load) in the design of railway track were investigated for various track design criteria. The research findings provide new and practical suggestions in the analysis and design of ballasted railway tracks.

This article provides a brief review of aspects of biophysical modelling in radiation biology. A major concern of radiation biology in the past half century has been the quantification of the health hazards of ionising radiations of different qualities and extrapolation of human cancer risks at high dose and dose rates to low dose and dose rates (UNSCEAR 1993). In the past decade with the accelerated progress in molecular biology techniques and advances in theoretical methods attention has become more focused on mechanistic studies and interpretation of effects of ionising radiation. To this end, track structure has provided a theoretical tool to investigate those parameters of ionising radiation that predominantly determine the nature and magnitude of the final effect (Vogelstein and Kinzler 1998).

Background: The South-west coast of India is known to have very high levels of natural Background radiation due to the monazite beach sand. Uranium is the heaviest trace element found in all terrestrial substances at varying levels with chemical and radio toxicities. It supports several short-lived radioisotopes in its decay series including radium. Uranium in drinking water is important in terms of the ingestion dose.Materials and Methods: The present study reports the results of uranium analysis of 346 drinking water samples from the three costal districts of Kerala using fission track registration technique.Results: Results obtained show that uranium concentrations vary from 0.31 mg/l to 4.92 mg/l equivalent to the specific activity of 3.9 Bq/m3 and 62 Bq/m3, respectively.Conclusion: The estimated daily intake of uranium through drinking water is lower than the recommended limits. The distribution of uranium in water bodies shows a heterogeneous nature of distribution.

A short survey on modern track maintenance methods is given, concentrating on the developments in recent years. The ongoing refinement of the machinery should be shown as the influence of ITsolutions should. On top the economic view to the track infrastructure is briefly demonstrated. Further developments in track hardware solutions must respect the obtained high level of track work mechanization. However, with respect to presentation time some other ongoing developments unfortunately are not discussed. Prominent amongst those are: the advent of high grade rail steels like heat-treated perlitic steels, the experiments with bainitic steels and the introduction of hydraulically driven turnouts with special high-speed-prone rail geometry or the latest machine sets for general subgrade rehabilitation.