Investigation of Mechanical Properties of Cryogenically Treated Music Wire

It has been reported that treating music wire (high carbon steel wire) by cooling to cryogenic temperatures can enhance its mechanical properties with particular reference to those properties important for musical performance. We use such wire for suspending many of the optics in Advanced LIGO, the upgrade to LIGO - the Laser Interferometric Gravitational-Wave Observatory. Two properties that particularly interest us are mechanical loss and breaking strength. A decrease in mechanical loss would directly reduce the thermal noise associated with the suspension, thus enhancing the noise performance of mirror suspensions within the detector. An increase in strength could allow thinner wire to be safely used, which would enhance the dilution factor of the suspension, again leading to lower suspension thermal noise. In this article we describe the results of an investigation into some of the mechanical properties of music wire, comparing untreated wire with the same wire which has been cryogenically treated. For the samples we studied we conclude that there is no significant difference in the properties of interest for application in gravitational wave detectors

A dissertation upon the economic organisation of the fluid mile industry in England and Wales 1900 - 1954

The story of the fluid milk industry (a term which I shall not attempt to define) during the past half century is indeed a rewarding source of study, for in it we may observe the working of almost every economic phenomenon and every form of economic organisation. We see an industry beginning in a state of absolute laissez-faire, and developing successively into a voluntary combination for collective bargaining purposes, a compulsory combination with statutory powers and a state controlledindustry under a centralised authority, finishing as a combination of the two latter; and being affected by and reacting to booms and depression, "dumping", under and. over production, free trade and protection, rationalisation and discriminating market policy. A more eventful history can hardly be envisaged. It is inevitable that a work of this nature should be primarily factual and historical: the very structure of the work is chronological. Nevertheless it is intended that critical comment and contemporary opinion will be included wherever possible. The immediate subject of this work, we have said, will be fluid milk. It would be unrealistic, however, to attempt to divorce this from the other products of the dairying industry, both because of the degree of substitution existing between the products and of the complex nature of the marketing organisations which have beenEvolved. The decision to deal with England and Wales only rather than Great Britain as a whole was dictated by the desire for simplicity of treatment and the availability of statistics. Except in two or three instances (which are clearly indicated) the figures quoted refer only to England and Wales

Characterisation of mechanical loss in fused silica ribbons for use in gravitational wave detector suspensions

The majority of work contained in this thesis involves characterisation of the mechanical losses in fused silica ribbon fibres to determine their potential for use in suspending the 40kg test masses for Advanced LIGO. The design of fibres is discussed here, demonstrating the advantages of rectangular cross sections over the circular cross sections already used in GEO600, with experimental work used to show the viability of this suspension scheme. The losses of a number of modes of oscillation of fibres were investigated using different suspension designs to reduce excess loss mechanisms. Measurements made of the material loss of the fused silica, using cantilever bending modes of a fibre held at one end, gave values slightly higher than those used in the design of noise curves for Advanced LIGO. The measurements also showed a reduced thermoelastic damping effect from that theoretically calculated from which an altered value for the Young’s modulus of the fibres was found compared to the value for bulk fused silica. Measurements performed using the violin modes and pendulum modes of the fibres showed that, while excess loss mechanisms were characterised and in the case of the violin mode measurement shown to be negligible, the level of dilution of loss calculated theoretically was not achieved. The source of increased loss is thought to be due to the energy being concentrated closer to lossy welded regions of the fibre. The losses measured for the linear pendulum were the lowest ever measured. Measurements of the vertical bounce mode of a small mass suspended between two fibres has shown clear evidence that there is no intrinsic stress dependence of the material loss of fused silica and has given further evidence that the majority of loss in the fibres comes from a thin highly dissipative layer on the surface. The strength of ribbon fibres has been shown to be sufficient to carry the working load of the Advanced LIGO masses, with a 20kg test suspension being created, however there was a wide variation in measured fibre breaking strengths thought to be due to bending in the fibre coupling longitudinal force into shear stress. Issues regarding thermal stress at welds are discussed with suggested solutions for construction of Advanced LIGO suspensions

On demand: can demand response live up to expectations in managing electricity systems?

Residential demand response (meaning changes to electricity use at specific times) has been proposed as an important part of the low carbon energy system transition. Modelling studies suggest benefits may include deferral of distribution network reinforcement, reduced curtailment of wind generation, and avoided investment in reserve generation. To accurately assess the contribution of demand response such studies must be supported by realistic assumptions on consumer participation. A systematic review of international evidence on trials, surveys and programmes of residential demand response suggests that it is important that these assumptions about demand response are not overly optimistic. Customer participation in trials and existing programmes is often 10% or less of the target population, while responses of consumers in existing schemes have varied considerably for a complex set of reasons. Relatively little evidence was identified for engagement with more dynamic forms of demand response, making its wider applicability uncertain. The evidence suggests that the high levels of demand response modelled in some future energy system scenarios may be more than a little optimistic. There is good evidence on the potential of some of the least ‘smart’ options, such as static peak pricing and load control, which are well established and proven. More research and greater empirical evidence is needed to establish the potential role of more innovative and dynami

Green job creation, quality and skills: A review of the evidence on low carbon energy. UKERC Technology and Policy Assessment.

The net employment impacts of a renewable energy or energy efficiency investment account both for jobs that are created, as well as jobs that might be displaced in other parts of the economy as a result of the investment. This report therefore addresses the following research question: How many jobs can be created by policy support for investment in low carbon energy and energy efficiency compared to supporting fossil fuel incumbents? The review identifies a variety of approaches used to estimate the quantity of low carbon energy job creation. It finds that much greater standardisation of methods would be desirable in order to compare how many jobs can be created by policies supporting low carbon energy and energy efficiency, both at a project scale and a wider societal level. Our findings also underline a relative lack of metrics and data measuring quality, skills, and geographic distribution of low carbon job creation, and these should be priority areas for further research

Electricity cost estimates: How accurate are they, and are they fit for purpose in policy analysis?

This thesis is concerned with the history of electricity generation costs, how they have changed over time, and the accuracy of forecasts of future costs. These costs are a critical input to policy, yet both estimates and forecasts have frequently proved to be wrong or have changed dramatically over relatively short timescales. The thesis presents evidence from three technology case studies (offshore wind, nuclear power and solar PV), supported by a review of the range of cost measures used in the economic, business and policy spheres, and the methodologies used to understand the factors that bear upon cost trajectories and approaches to forecasting future costs. Drawing upon the evidence from the case studies, the thesis examines how cost forecasts have changed over time, the (frequently wide) range of forecasts, the sources of errors, and how policy has responded to uncertainty and changes in both cost estimates and forecasts. The findings address the limitations of commonly used cost metrics, challenge assumptions that costs will necessarily fall, discuss the meaning of regulatory certainty in the face of uncertain future costs, and emphasise the importance of context (why estimates are commissioned, and by whom, and also who they are undertaken by). The evidence suggests that the co-presentation and use of estimates and forecasts for technologies with very different technical and financial characteristics implies significantly more comparability between them than is wise, and can convey the message that the underlying uncertainties are similar, when in fact the reasons may be fundamentally different in character. This highlights how important an understanding of technology characteristics is when deriving estimates and forecasts, not simply because those characteristics bear upon the numerical values of the results, but because of the influence they have on the nature of the uncertainty of those results.Open Acces