A High Stability Optical Shadow Sensor with Applications for Precision Accelerometers

Gravimeters are devices which measure changes in the value of the gravitational acceleration, \textit{g}. This information is used to infer changes in density under the ground allowing the detection of subsurface voids; mineral, oil and gas reserves; and even the detection of the precursors of volcanic eruptions. A micro-electro mechanical system (MEMS) gravimeter has been fabricated completely in silicon allowing the possibility of cost e-effective, lightweight and small gravimeters. To obtain a measurement of gravity, a highly stable displacement measurement of the MEMS is required. This requires the development of a portable electronics system that has a displacement sensitivity of $\leq 2.5$ nm over a period of a day or more. The portable electronics system presented here has a displacement sensitivity $\leq 10$ nm$/\sqrt{\textrm{Hz}}$ ($\leq 0.6$ nm at $1000$ s). The battery power system used a modulated LED for measurements and required temperature control of the system to $\pm$ 2 mK, monitoring of the tilt to $\pm$ 2 $\mu$radians, the storage of measured data and the transmission of the data to an external server.Comment: 8 Pages, 12 figures, 5 equations, currently submitted and under review at IEEE Sensors SIE

Field tests of a portable MEMS gravimeter

Gravimeters are used to measure density anomalies under the ground. They are applied in many different fields from volcanology to oil and gas exploration, but present commercial systems are costly and massive. A new type of gravity sensor has been developed that utilises the same fabrication methods as those used to make mobile phone accelerometers. In this study, we describe the first results of a field-portable microelectromechanical system (MEMS) gravimeter. The stability of the gravimeter is demonstrated through undertaking a multi-day measurement with a standard deviation of 5.58 × 10−6 ms−2 . It is then demonstrated that a change in gravitational acceleration of 4.5 × 10−5 ms−2 can be measured as the device is moved between the top and the bottom of a 20.7 m lift shaft with a signal-to-noise ratio (SNR) of 14.25. Finally, the device is demonstrated to be stable in a more harsh environment: a 4.5 × 10−4 ms−2 gravity variation is measured between the top and bottom of a 275-m hill with an SNR of 15.88. These initial field-tests are an important step towards a chip-sized gravity senso

Characterizing the energy use of disabled people in the European Union towards inclusion in the energy transition

Designing environmental policy to take account of social difference is increasingly recognized as essential to address both effectiveness and justice concerns. So far there is limited research on the experiences of disabled people in the environmental literature, amounting to a failure to recognize this substantial constituency. Here we compare disabled households’ embodied energy use, income, risk of poverty and energy poverty, and other socio-demographics with other households in the European Union. We find that households including an economically inactive disabled person earn less and consume 10% less energy than other households, and are more likely to experience energy poverty. Disabled households have lower consumption than other households in most categories, with the exception of basic consumption such as food, energy at home (gas and electricity), water and waste services: in effect they have less—and sometimes inadequate—access to resources. We conclude that more attention should be paid to disabled households needs to ensure a just energy transition

Microelectromechanical system gravimeters as a new tool for gravity imaging

A microelectromechanical system (MEMS) gravimeter has been manufactured with a sensitivity of 40 ppb in an integration time of 1 s. This sensor has been used to measure the Earth tides: the elastic deformation of the globe due to tidal forces. No such measurement has been demonstrated before now with a MEMS gravimeter. Since this measurement, the gravimeter has been miniaturized and tested in the field. Measurements of the free-air and Bouguer effects have been demonstrated by monitoring the change in gravitational acceleration measured while going up and down a lift shaft of 20.7 m, and up and down a local hill of 275 m. These tests demonstrate that the device has the potential to be a useful field-portable instrument. The development of an even smaller device is underway, with a total package size similar to that of a smartphone

Power scalable TEM(oo) CW Nd: YAG laser with thermal lens compensation

We present finite-element analyzes and experimental results to validate our approach for building high-power single-mode Nd:YAG lasers. We show that the thermooptical and thermomechanical properties of a slab laser can be controlled. This is essential for the use of the proposed unstable resonator. We include demonstration of an efficient subscale laser operating at 20 W TEM00.D. Mudge, M. Ostermeyer, P. J. Veitch, J. Munch, B. Middlemiss, D. J. Ottaway and M. W. Hamilto

A study of fuel poverty and low-carbon synergies in social housing

This socio-technical pilot involved qualitative interviews with social housing tenants, combined with basic energy modelling of the individual dwellings to estimate the carbon emissions of that house. The study aimed to investigate the relationship between fuel poverty and carbon-saving synergies in the UK domestic housing stock. Fuel poverty, the circumstance where a household spends more than 10% of its income on energy bills, is predicted as being 21% of the entire domestic stock. The fuel poor behaviours described in this study, including frugality and rationing of energy use, may become more common, and even be seen as the “norm”. If domestic energy bills increase with predictions, the number of fuel poor households will continue to rise. It is likely that their practices will become more diverse. This diversity is important as it will affect not only the choice of measures for reducing energy consumption but also the likely post-measure “rebound effect”, where a perceived energy saving might not be achieved as households increase their energy use directly, or indirectly, as a result of having lower energy bills. The study found that “electricity as entertainment” is very apparent in low-income homes, particularly those with children. This can have a significant impact on the household’s fuel poverty status. It is important not to discount this effect as the choices for reducing fuel poverty may not only be related to building refurbishment. This study concludes that lack of energy inefficiency is not the main driver of fuel poverty in the UK. Small changes in the efficiency of the UK stock have had minimal impact on fuel poverty numbers because this is driven by gas prices. But if large-scale changes were made to such homes then it may be possible to ameliorate the effect of rising fuel prices, though without eliminating fuel poverty altogether. The work ascertained that the fuel poor do not recognise themselves as living ‘low-carbon lifestyles’ but it seems likely that they do from the frugal responses that our sample display. Helping those in fuel poverty to recognise this, and rewarding this through policy, could be a positive way of encouraging continued action If a substantial impact to both fuel poverty and domestic carbon emissions is to be made, large-scale changes to buildings are necessary. Existing energy behaviour, energy frugality (as governed by income) and the response of the occupant to any potential energy-saving improvement will not be universal across the stock. Given the fuel poverty context, the authors suggest that the proposed 2011 Energy Act Green Deal is not suitably structured for achieving large-scale reductions in fuel poverty and domestic carbon emissions. The provision intends to provide loans of up to £6.500 to eliminate the need to pay upfront for energy efficiency measures. The cost of repayment should be covered by electricity bill savings. If large-scale measures are needed to have a genuine, and long lasting, effect, then £6,500 per home is not likely to be sufficient for fuel poor social housing tenants to rise out of fuel poverty. It is currently unclear whether the Energy Company Obligation (ECO) will be sufficient to compensate for any of the weaknesses of the Green Deal when applied to fuel poor homes. ECO will place one or more obligations on energy companies requiring them to facilitate the installation of energy efficiency measures in homes

Plugging the gap between energy policy and the lived experience of energy poverty: five principles for a multi-disciplinary approach

In this chapter, we illustrate the value of a multi-disciplinary approach to energy poverty policy, drawing on insights from research into the lived experience of energy poverty in three European countries. We argue that understanding the lived experience of energy poverty is critical in designing energy policies, which are fair, effective and aligned with people’s daily lives. In addition, we contend that bringing together a range of disciplines to examine dimensions of the lived experience of energy poverty (such as housing, employment, education, social policy, health, energy etc.) is essential to give breadth to our understanding of this challenging, and multi-faceted condition. We propose five principles for policy design, informed by our multi-disciplinary understanding of the lived experience. These principles can be applied at a range of scales (local, regional, national and European) to help ensure that the energy poor are both well served, and represented, by energy policy

Silt curtains - a review of their role in dredging projects

As environmental mitigation associated with dredging and marine construction activities becomes ever more a focus of attention, the use of silt curtains to contain fine material locally to the dredging operation has increased. A silt curtain is typically simple in design, comprising of a geo-textile sheet attached to floats that are weighed down to the sea floor and anchored in place. The expected result is to prevent the transport of sediment out of the work site and into the surrounding environment. However, few documents exist that consolidate the current understanding of the use of curtains and the controlling factors associated with the deployment of them, including consideration of their purpose, design, development and limitations. A cynic’s view is that silt curtains are often installed to comply with regulatory constraints and may offer limited practical value, especially when they are left unmaintained. Poor understanding of silt curtain design and limitations often means they are installed in unsuitable environments, resulting in unsatisfactory performance. Critically, once a curtain is installed; without good management and regular maintenance, the geo-textile will often perish leading to a significant reduction in its effectiveness. Different installation methods exist along with multiple configurations; consideration of the environmental conditions should be made prior to the design and installation of a silt curtain. This paper will consider a range of parameters that affect the effectiveness of silt curtains