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.

Current practices in railway TRACK analysis and DESIGN are reviewed and discussed in this paper. The mechanical behavior of railway TRACK structure comprising of various components has not been fully understood due to the railway TRACK structural complexity. Although there have been some improvements in the accuracy of current TRACK DESIGN methods in recent decades, there are still considerable uncertainties concerning the accuracy and reliability of the current methods. This indicates a need for a thorough review and discussion on the current practices in the analysis and DESIGN of railway TRACK systems. In this paper, railway DESIGN approaches proposed by various standards along with the results of a wide range of technical researches are studied and necessary suggestions are made for the improvement of current practices in the analysis and DESIGN of railway TRACKs.

In the railway industry, TRACK circuits are of great significance to ensure safe transportation and avoid crashes and accidents. These circuits majorly determine the existence of a train on sections of rail path called TRACKs using the conductivity properties of rail steel as a part of the circuit. In this paper, the problem of high implementation costs and blind spots for audio frequency TRACK circuits is considered and solved. As the novelty of this work, a new structure for frequency TRACK circuits is proposed leading to the elimination of all on-rail receivers and precise train positioning. The rail resistance is taken into account in the transmitter circuit to affect the amplitude of signals based on the traveled path. Moreover, a new topology is suggested to amend the audio frequency TRACK circuit in order to decrease costs and remove blind spots as well. Compared to other TRACK circuits, the proposed method has the advantage of lower costs, and train’s location approximation without the use of GPS (global positioning system). The proposed method works with signals with frequencies within 80 to 180 Hz and the maximum length of TRACK sections is set to 900 meters to restrict rail’s resistance effects. Finally, in the simulation section, the efficiency of the proposed method is studied, and its capability is proved.

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.

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).