Condition Monitoring of Power Cables

A National Grid funded research project at Southampton has investigated possible methodologies for data acquisition, transmission and processing that will facilitate on-line continuous monitoring of partial discharges in high voltage polymeric cable systems. A method that only uses passive components at the measuring points has been developed and is outlined in this paper. More recent work, funded through the EPSRC Supergen V, UK Energy Infrastructure (AMPerES) grant in collaboration with UK electricity network operators has concentrated on the development of partial discharge data processing techniques that ultimately may allow continuous assessment of transmission asset health to be reliably determined

Profit, reputation and ‘doing the right thing’: Convention theory and the problem of food waste in the UK retail sector

In 2014, Tesco – one of the world’s largest food retailers – revealed that it had generated almost 57,000 tonnes of food waste in its UK operations over the previous twelve-month period. This shocking statistic added to existing evidence of a significant environmental and social problem in the UK and across the world. This paper utilises convention theory to examine the role of major retailers in the context of this global problem and assesses their motivations for acting on food waste. Drawing on interviews with key stakeholders (including major retailers), the analysis investigates their main justifications for action on food waste. It finds that retailers mostly appealed to three conventions or ‘orders of worth’ (civic, market and opinion) and used these as a basis for their commitment to food waste reduction. We argue that the combination of these different justifications is feasible and necessary in the context of the retail sector but that they may also lead to some unintended consequences (in the retail sector and beyond). Crucially, we demonstrate how the dilution of civic justifications (by their financial and reputational counterparts) might produce negative outcomes and inaction as retailers attempt to adhere to the so-called ‘food waste hierarchy’. The paper highlights the continuing significance of convention theory as a framework for analysing possible responses to the social and environmental challenges confronting global agro-food systems

The role of local labour market conditions and pupil attainment on post-compulsory schooling decisions

Purpose The purpose of this paper is to assess the role of local labour market conditions and pupil educational attainment as primary determinants of the post-compulsory schooling decision. Design/methodology/approach Through the specification of a nested logit model, the restrictive independence of irrelevant alternatives (IIA) assumption inherent in the multinomial logit (MNL) model is relaxed across multiple unordered outcomes. Findings The analysis shows that the factors influencing schooling decisions differ for males and females. For females, on average, the key drivers of the schooling decision are expected wage returns based on youth educational attainment, attitudes to school and parental aspirations, rather than local labour market conditions. For males, higher local unemployment rates encourage greater investment in education. Originality/value The contribution of this paper to the existing literature is threefold. First, a nested logit model is proposed as an alternative to a MNL. The former can formally incorporate the structured and sequential decision-making process that youths may engage with in relation to the post-compulsory schooling decision, as well as relaxing the restrictive IIA assumption inherent in the MNL across multiple unordered outcomes, an issue the authors discuss in more detail in the Methodology section below. Second, the analysis is based on extremely rich socio-economic data from the Longitudinal Study of Young People in England, matched to local labour market data and administrative data from the National Pupil Database and Pupil Level Annual School Census, which provide a broad set of unusually high-quality measures of prior attainment. The authors argue that such high-quality data and an appropriate model specification allows identification of the determinants of the post-compulsory decision in a more detailed manner than many previous analyses. Third, the data have the scale necessary to consider whether the determinants of post-compulsory schooling decisions vary by gender, a particularly important issue given the differential education participation rates of males and females (e.g. in this cohort, females are about 10 percentage points more likely to go on to higher education in the UK than males), and the gendered choices of occupation (see, e.g. Bertrand, 2011). The work will, therefore, provide recent empirical evidence from England on gender differences in the determinants of education choices. Office for Manpower Economic

Modelling of Partial Discharge Activity in a Cavity within a Dielectric Insulation Material

The pattern of partial discharge?PD?occurrence at a defect site within a solid dielectric material is influenced by the conditions of the defect site. This is because the defect conditions such as its size and location determine the electric field distributions at the defect site which influence the patterns of PD occurrence. A model for a spherical cavity and ellipsoidal cavity within a homogeneous dielectric material has been developed by using Finite Element Analysis (FEA) software. The model is used to study the influence of different conditions of the cavity on the electric field distribution in the cavity and the PD activity. Also, experimental measurements of PD in spherical cavity and ellipsoidal cavity of different size within a dielectric material are detailed

A study of column separation accompanying pressure transients in an aviation kerosene pipeline

Column separation on both the upstream and downstream sides of a valve in an aviation kerosene pipeline was the subject of an investigation involving the method of characteristics to solve the partial differential equations governing pressure transient propagation. Particular attention was given to obtaining accurate velocity results at the instant the predicted pressure at a section reached vapour pressure. A test rig utilizing L.56 aluminium alloy fuel piping and other aircraft standard components and pumping Aviation Kerosene Specification 2494, was employed to investigate the phenomenon and test the computing procedures. For separation upstream of a valve following closure, a comparison of the computed and observed results indicated an accuracy within 3% for the first peak following valve closure and 5% for the cavity duration. Computed results within 10% of the observed were obtained for the later peaks following cavity collapse.Observation and filming of the sequence of events downstream of the valve during and following closure indicated that the air released during initial separation remained out of solution. The effect of this air was significant but could be included, in terms of its partial pressure, in the cavity boundary equations. The predicted cavity collapse pressures were consistently above those observed. Predicted values of maximum and minimum pressures, and their event times, following valve closure were, at worst, within 10% of the observed results. Analysis of the released gas indicated that it had normal air composition. Measurement of column velocity from the films and the use of a hot film probe and anemometer supported the assumptions made with reference to column motion. The hot film probe results demonstrated that this flow measurement technique was practical in this application

Occupational sex-segregation, specialized human capital and wages: evidence from Britain

Female-dominated occupations are poorly paid, but there is disagreement about why. Sociological explanations argue that pay in such occupations is low because society undervalues 'women's work', while economic theory argues that this is due to scant requirements for specialized skills. This article sheds light over these debates by examining the impact of occupational feminization on wages in Britain and exploring the mechanisms that produce it, using innovative statistical models that account for both observable and unobservable skill. Results confirm that occupational sex-segregation explains a sizeable portion of the gender wage gap and that wages in female-dominated occupations are lower than wages in other occupations. Inconsistent with human capital theory, low pay in female-dominated occupations cannot be explained fully by low skill specialization or by observable or unobservable characteristics of their workers. Remaining wage penalties in such occupations are consequently taken as evidence of institutional devaluation of 'women's work'