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Publications (33)
In order to improve the utilization rate of expensive and very limited urban land, a new structure system, underground metro depot, has been developed and applied in several cities in China. The underground metro depot, which is built underground, can be multiple stories, and allows other developments on top, has become increasingly popular in rece...
In this study, the possibility of using the rail vibration frequency to assess the longitudinal temperature force on the rail of ballasted track was investigated experimentally. An empirical formula was subsequently derived to link the frequency index to multiple factors, including the longitudinal temperature force, under-rail stiffness, and faste...
Acoustic Deterrent Devices (ADDs) are used worldwide to deter pinnipeds from predating fish-aquaculture facilities. Desk-based noise-propagation modelling of six commercial ADD models, and a ‘fictional’ ADD was performed, the latter involving alternating source level, frequency, duty cycle, noise-exposure duration, and number of ADDs active simulta...
Little is known about localized, near-field soundscapes during offshore hydrocarbon drilling campaigns. In the Dogger Bank, North Sea, underwater noise recordings were made 41–60 m from the drill stem of the Noble Kolskaya jack-up exploration drilling rig. The aims were to document noise received levels (RLs) and frequency characteristics of rig-as...
The modelled acoustic characteristics of three Acoustic Harassment Devices (AHDs) deployed from a fully operational salmonid fish farm, located in the Sound of Mull, Scotland (UK) are presented, using empirical seabed and water column measurements at the same location. In the Beaufort Sea state 0, the depth range of 10--50 m is the maximum range at...
Background
A novel tunable negative stiffness nonlinear electromagnetic isolator is presented, it includes a vertical positive stiffness spring, an electromagnetic spring constructed by two permanent magnets and an electromagnet. The electromagnetic isolator can act as a passive isolator or a semi-active control one.
Method
The mathematical expres...
Underground railway vibration source strength is one of the key values used for environmental impact assessment and the evaluation of mitigation measure's performance. However, currently there is no international standard of measuring the underground railway vibration source strength for such purposes. The available local standards and industrial g...
Active control is an effective way to suppress low-frequency mechanical vibration. However, with applications to submarine equipment, there are still some shortcomings due to vibration coupling and multifrequency complex excitation. In this paper, a novel hybrid improved adaptive control strategy, feedback and online identification filtered-x LMS,...
This paper presents a novel variable stiffness isolator designed by magnetic springs in parallel with linear positive stiffness spring. Firstly, the two-degree-of-freedom vibration system model with variable stiffness magnetic isolator is established. The amplitude frequency characteristic equation of the system is derived based on the multi-harmon...
Chaotic vibration has become increasingly popular in the study of acoustic and vibration engineering. Many engineering designs have taken advantage of the special characteristics of chaos, and deliberately introduced it into the system to improve efficiency. As an important component, leaf springs have long been used in the suspension system of whe...
A trench can act as a barrier to ground vibration and is a potential mitigation measure for low frequency vibration induced by surface railways. However, to be effective at very low frequencies the depth required becomes impractical. Nevertheless, for soil with a layered structure in the top few metres, if a trench can be arranged to cut through th...
Railway-induced ground vibration is often associated with sites with soft ground. Stiffening of the subgrade beneath the railway track is one particular measure that has potential to reduce the vibration level at such sites. However, the mechanisms behind this reduction are not well understood. Here, the effects are examined in the context of two a...
This dataset includes the raw data for the figures published in "Mitigation of railway-induced vibration by using subgrade stiffening", Soil Dynamics and Earthquake Engineering
The need to measure the dynamic void fraction (the proportion of flowing bubbly liquid that is gas) is common across many power, processing and manufacturing industries. Many such pipelines and liquids are optically opaque, and work on margins that require a low cost solution that is not commensurate with the size of the challenge. Such a solution...
There is a need to measure the quantity of gas bubbles flowing in liquid-filled pipelines in many power, processing and manufacturing industries. This paper outlines the theoretical foundation for one aspect of a candidate bubble detector technique that was commissioned for Oak Ridge ational Laboratory’s Spallation Neutron SourceTarget Test Facilit...
The effectiveness of heavy masses next to the track as a measure for the reduction of railway induced ground vibration is investigated by means of numerical simulations. It is assumed that the heavy masses are placed in a continuous row along the track forming a wall. Such a continuous wall could be built as a gabion wall and also used as a noise b...
On sites with soft ground, stiffening of the subgrade beneath railway track has been associated with a reduction inground-borne vibration. However, the mechanisms behind this reduction are not well understood. Here, the effects are examinedin the context of two alternative approaches: (i) subgrade stiffening, where the soil directly under the track...
Railway induced ground-borne vibration at low frequency, below about 50 Hz, has a great impact on the nearby environment. In many cases, it is recognised as a major source of annoyance for line-side residents. Within the EU research project RIVAS (Railway Induced Vibration Abatement Solutions), a number of mitigation methods were proposed and inves...
This paper studies the efficiency of stiff wave barriers for the mitigation of railway induced vibrations. Coupled finite element–boundary element models developed at KU Leuven and ISVR are employed; these models have been cross–validated within the EU FP7 project RIVAS (Railway Induced Vibration Abatement Solutions). A first mitigation measure con...
To reduce railway induced low frequency vibration, two mitigation measures - open trenches and buried soft wall barriers have been studied in this paper by using coupled finite element-boundary element models. These models were developed at KU Leuven and ISVR, and have been cross-validated within the EU FP7 project RIVAS (Railway Induced Vibration...
Equations for the nonaxisymmetric modes that are axially and circumferentially propagating in a liquid-filled tube with elastic walls surrounded by air/vacuum are presented using exact elasticity theory. Dispersion curves for the axially propagating modes are obtained and verified through comparison with measurements. The resulting theory is applie...
The most popular technique for estimating the gas bubble size distribution (BSD) in liquids is through the inversion of measure attenuation and/or sound speed of a travelling wave. The model inherent in such inversions never exactly matches the condition of the measurement, and the size of the resulting error (which could well be small in quasi-fre...
This paper describes a demonstration and explanation of sound absorption in water due to bubbles, and in air due to a fog of water droplets. It is suitable for 10-12 year olds, but the paper indicates where further exploration of the simplifications in the explanations provided for that age range would allow the demonstration to be used for undergr...
This paper uses a finite element method (FEM) to compare predictions of the attenuation and sound speeds of acoustic modes in a fluid-filled pipe with those of the analytical model presented in the first paper in this series. It explains why, when the predictions of the earlier paper were compared with experimental data from a water-filled PMMA pip...
A real-world contract to exploit the absorption of acoustic waves by bubbles (at SNS) therefore produced the two-pipe apparatus which was readily adapted for the TV demonstration. The equipment was dismantled and driven to the Herefordshire on 19 February 2010. It was a snowy evening, and the equipment was unloaded from the car. Bubbles are well-kn...
Del Grosso's [Acustica 24, 299-311 (1971)] formulation, which predicts the phase speed of propagating axisymmetric modes inside a liquid-filled tube, is here extended to the complex domain in order to predict the attenuation, as well as the sound speed, of the modes as a function of frequency. Measurements of the sound speeds and the attenuations o...
Theoretical investigations are undertaken with the propagation of sound inside the tube filled with liquid. Previous theoretical works by Del Grosso's, Lafleur and Shields, and Elvira-Segura are here reviewed and extended to the complex domain in order to predict the attenuation, as well as the sound speed, of the modes as a function of frequency....