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.
Acoustics and Sustainability : How should acoustics adapt to meet future demands ? Experimental and numerical analyses of a floating slab track
A vibration isolated rail trackform, or Floating Slab Track (FST) was designed using empirical, numerical and experimental techniques. This paper focuses on the correlation between modal testing and Finite Element Analysis (FEA) of the FST. The modeshapes of the FST in the frequency range of 5 Hz to 250 Hz are discussed and the effects of adding the unsprung mass of a rail vehicle are explored within the framework of the FE method. Vibration levels measured at a slab during a train pass-by are presented. Characteristics of the pass-by spectra are explained with the developed model.
Unidirectional hexagonal rare-earth disilicide nanowires on vicinal Si(100)-2×1
Rare-earth disilicide nanowires grown on vicinal Si(100) with a miscut of 2–2.5° toward the [110] azimuth at 600 °C were studied by scanning tunneling microscopy and compared with those grown on flat Si(001). In contrast to rare-earth disilicide nanowires grown on flat Si(100) surfaces, the nanowires grow unidirectionally along the [01̄1] direction of the vicinal Si(100) surface. Rare-earth disilicide nanowires form bundles composed of single nanowire units on both flat and vicinal surfaces. Yet, on the vicinal surface, the bundle width is comparable to the width of the terrace. The average nanowire length on the vicinal substrate is longer than that on the flat substrate. Scanning tunneling spectroscopy shows that the rare-earth disilicide nanowires have metallic properties.