The sound field due to an arbitrarily oriented quadrupole above an impedance ground is investigated. To simplify the analysis, the atmospheric and topographical effects on sound propagation are ignored. Two different methods are developed to calculate the sound field. First, an asymptotic method is used to derive a close-form analytic solution. Second, a fast field program (quad-FFP) has been developed for numerical computations of the sound field. It is found that numerical results from both methods agree well. In a recent development, it has been shown that the analytic solution of the sound field due to an arbitrarily oriented dipole can be written in the classical form similar to that due to a monopole. However, it is not possible to write the solution in such a form for the case of an arbitrarily oriented quadrupole, but rather the total sound pressure is augmented by two extra terms which are particularly important at a small separation between the source and receiver.

Recently there has been interest in using the velocity of elastic waves to deduce soil physical properties. We wanted to validate the suggestion that the small strain shear modulus has a relatively simple linear relationship with penetrometer resistance. We were also interested in testing published equations for predicting shear wave velocity with an independent data set. Three soils were investigated in this study: a loamy sand soil and two silty clay loam soils. The soils were packed into cores with vertical axial stresses of 30, 200, or 1000 kPa. Following saturation, they were drained to a range of matric potentials between −10 and −500 kPa. After equilibration, we measured the velocities of shear (S wave) and compression (P wave) waves as well as the penetrometer resistances. Our data confirmed a previous proposal that the penetrometer resistance was an approximately linear function of the small strain shear modulus but tested the relationship by direct measurement. The relationships were found to have some sensitivity to soil type. Nevertheless, we show for the first time that there is considerable potential for using S wave velocity to deduce penetrometer resistance with a calibration that is relatively insensitive to soil type. Although estimation of the matric potential with either shear or compression wave velocity was found not to be very accurate, the possibility for estimating the matric potential from an elastic wave velocity given a priori knowledge of the void ratio is an interesting opportunity.

We investigated the effect of soil organic carbon (SOC) on the consolidation behaviour of soil from two long term field experiments at Rothamsted; the Broadbalk Wheat Experiment and Hoosfield Spring Barley. These experiments are located on soil with similar particle size distributions, and include treatments with SOC contents ranging from approximately 1?3.5 g/100 g. Soils taken from plots with contrasting SOC contents were compressed and deformed in a triaxial cell and the normal consolidation and critical state lines were determined. We found that the compression index was independent of SOC, but the void ratio at any given effective stress was highly correlated with organic carbon content. By comparison with uniaxial compression data, the apparent influence of SOC on the compression index is likely to be due to its effect on soil hydraulic properties rather than any intrinsic effects of strength. The plastic limit test appears to be a useful and simple test to allow direct comparison of soil physical behaviour and expected soil density.

The ageing of populations is increasing pressure on health and social care systems. Potentially, assistive technologies are a way to support the independence of older adults in their daily activities. Among existing assistive technologies, ambient sensing technologies have received less attention than wearable systems. Moreover, there has been little research into cheaper technologies capable of using multiple modalities. A systematic review of the acceptability of assisted living or smart homes in the United Kingdom and the simultaneous use of sounds and vibrations in remote monitoring of assisted living or smart homes will inform and encourage the use of digital monitoring technologies. The acceptability of sensing technologies depends on whether there is any social stigma about their use, for example, the extent to which they invade privacy. The United Kingdom studies reviewed suggest a lack of measurements of the perceived efficacy or effectiveness of the monitoring devices. The primary use of vibration or acoustic technologies has been for detecting falls rather than monitoring health. The review findings suggest the need for further exploration of the acceptability and applicability of remote monitoring technologies, as well as a need for more research into the simultaneous use of sounds and vibrations in health monitoring.