The force transmissibility of a floating slab track
The force transmissibility of a track isolation system is the ratio of the force transmitted to the track bed over the force applied at the railheads. This paper focuses on the force transmissibility of a double-tie or ‘mini-slab’ floating slab track installation. The power spectral densities of the forces transferred to ground due to ‘white noise’ force sources at the rail heads are calculated. Analytical models and the Finite Element (FE) method are used to analyse a floating slab track supported on a rigid foundation. The effect of rail fastener stiffness is discussed. The influence of the flexibility of the floating slabs and the effects of a non-rigid foundation on the force transmissibility is investigated within the framework of the FE method.
RAIL SYSTEM NOISE AND VIBRATION CONTROL
Control of noise and vibration emitted by steel wheel and rail transportation systems has a long history of designs and techniques, some of which were dismal failures and some which worked very well. Many of the early efforts had a valid technical base for the design, however, there were also many based on intuition or ideas with great expectations, but which had no real technical basis. In the last four decades the technology and materials used for rail noise and vibration control, particularly for the control of groundborne vibration from rail systems, has developed and benefited from thoughtful technical analyses and application of simple engineering principles. These also were not always successful in all respects but provided for a continuing development of the technology with ever-improving success and performance. Included in this presentation are a review of the development of rail noise and vibration control systems, including the lightweight, undamped concrete floating slab track for reduction of groundborne noise and vibration, and of the development of structurally integrated sound barriers with absorption materials for control of airborne sound. The presentation includes anecdotes and discussion of some of the unexpected results from new design installations, an outline of design progress and application extensions, and review of the concepts and designs which are successful and currently in use by rail systems located in many different parts of the world.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.