Flywheel Energy Storage Systems for Rail

In current non-electrified rail systems there is a significant loss of energy during vehicle braking. The aim of this research has been to investigate the potential benefits of introducing onboard regenerative braking systems to rail vehicles. An overview of energy saving measures proposed within the rail industry is presented along with a review of different energy storage devices and systems developed for both rail and automotive applications. Advanced flywheels have been identified as a candidate energy storage device for rail applications, combining high specific power and energy. In order to assess the potential benefits of energy storage systems in rail vehicles, a computational model of a conventional regional diesel train has been developed. This has been used to define a base level of vehicle performance, and to investigate the effects of energy efficient control strategies focussing on the application of coasting prior to braking. The impact of these measures on both the requirements of an energy storage system and the potential benefits of a hybrid train have been assessed. A detailed study of a range of existing and novel mechanical flywheel transmissions has been performed. The interaction between the flywheel, transmission and vehicle is investigated using a novel application-independent analysis method which has been developed to characterise and compare the performance of different systems. The results of this analysis produce general ‘design tools’ for each flywheel transmission configuration, allowing appropriate system configurations and parameters to be identified for a particular application. More detailed computational models of the best performing systems have been developed and integrated with the conventional regional diesel train model. The performance of proposed flywheel hybrid regional trains has been assessed using realistic component losses and journey profiles, and the fuel saving relative to a conventional train quantified for a range of energy storage capacities and power-train control strategies

Essays on the Effects of Macroeconomic Shocks

This thesis explores the effects of macroeconomic shocks in different contexts. In Chapter 2, I estimate the effects of monetary policy shocks on firm entry and exit rates, and develop a New Keynesian firm-dynamics model that qualitatively matches the empirical responses. I find that accounting for responses along the entry and exit margins does not appreciably change the predictions of the standard (representative-agent) New Keynesian model. Chapter 3 develops algorithms to facilitate Bayesian inference in structural vector autoregressions (SVARs) that have been identified using sign and zero restrictions. Chapter 4 reviews the literature on robust Bayesian inference as a tool for global sensitivity analysis and statistical decision-making under ambiguity. It also presents a self-contained discussion of three different approaches to conducting robust Bayesian inference in set-identified SVARs, along with an empirical example. Chapter 5 explains how to conduct ‘robust’ (multiple-prior) Bayesian inference in set-identified proxy SVARs, and explores the frequentist properties of this approach when the proxies are only weakly correlated with the structural shocks of interest. It illustrates the approach by estimating the effects of shocks to average income tax rates in the United States. Chapter 6 explores issues related to identification and inference in SVARs under ‘narrative restrictions’, which are restrictions on functions of the structural shocks in particular periods

Philosophy with children : helping designers cooperate with children

Engaging children in design through in-depth interviews is coming to prominence in the IDC community, which increasingly engages with issues about understanding the children's world. To date, research in this area has primarily focused on engaging children using techniques somehow similar to adult-techniques (moodboards, brainstorming, laddering,...). However, questioning or interviewing children is fraught with difficulties. The proposed workshop seeks to explore where and how a philosophy with children methodology can be adapted for design, exploring themes such as Socratic Attitudes, wondering, and question types. This workshop aims to build an interdisciplinary community of researchers, designers, and practitioners to share and discuss their work and experiences

Social encounter networks : characterizing Great Britain

A major goal of infectious disease epidemiology is to understand and predict the spread of infections within human populations, with the intention of better informing decisions regarding control and intervention. However, the development of fully mechanistic models of transmission requires a quantitative understanding of social interactions and collective properties of social networks. We performed a cross-sectional study of the social contacts on given days for more than 5000 respondents in England, Scotland and Wales, through postal and online survey methods. The survey was designed to elicit detailed and previously unreported measures of the immediate social network of participants relevant to infection spread. Here, we describe individual-level contact patterns, focusing on the range of heterogeneity observed and discuss the correlations between contact patterns and other socio-demographic factors. We find that the distribution of the number of contacts approximates a power-law distribution, but postulate that total contact time (which has a shorter-tailed distribution) is more epidemiologically relevant. We observe that children, public-sector and healthcare workers have the highest number of total contact hours and are therefore most likely to catch and transmit infectious disease. Our study also quantifies the transitive connections made between an individual's contacts (or clustering); this is a key structural characteristic of social networks with important implications for disease transmission and control efficacy. Respondents' networks exhibit high levels of clustering, which varies across social settings and increases with duration, frequency of contact and distance from home. Finally, we discuss the implications of these findings for the transmission and control of pathogens spread through close contact

Turning Up the Heat on Energy Monitoring in the Home

The use of domestic electrical energy monitoring systems is becoming more common however gas usage has received comparatively little attention. This paper presents a new technique for monitoring gas-powered heating and hot water usage in the home integrated into a prototype energy monitoring platform. Compared to usual meter-based approaches this technique provides finer-grained usage data and uses simple temperature sensors. The main motivation for this work is to provide more meaningful energy information to users for inclusion in novel mobile and embedded applications. This is part of ongoing work which aims to reduce energy use among teenagers in the UK and make lasting attitude changes. The development and findings from a prototype deployed in a typical UK house over 7 days are presented. The findings highlight the utility of the technique and simplicity of the sensing approach. The novel requirements that inspired the development of this technique are also presented

Constructing the Cool Wall: A Tool to Explore Teen Meanings of Cool

This paper describes the development and exploration of a tool designed to assist in investigating ‘cool’ as it applies to the design of interactive products for teenagers. The method involved the derivation of theoretical understandings of cool from literature that resulted in identification of seven core categories for cool, which were mapped to a hierarchy. The hierarchy includes having of cool things, the doing of cool activities and the being of cool. This paper focuses on a tool, the Cool Wall, developed to explore one specific facet of the hierarchy; exploring shared understanding of having cool things. The paper describes the development and construction of the tool, using a heavily participatory approach, and the results and analysis of a study carried out over 2 days in a school in the UK. The results of the study both provide clear insights into cool things and enable a refined understanding of cool in this context. Two additional studies are then used to identify potential shortcomings in the Cool Wall methodology. In the first study participants were able to populate a paper cool wall with anything they chose, this revealed two potential new categories of images and that the current set of images covered the majority of key themes. In the second study teenagers interpretations of the meaning of the images included in the Cool Wall were explored, this showed that the majority of meanings were as expected and a small number of unexpected interpretations provided some valuable insights

A low pre-infall mass for the Carina dwarf galaxy from disequilibrium modelling

Dark matter only simulations of galaxy formation predict many more subhalos around a Milky Way like galaxy than the number of observed satellites. Proposed solutions require the satellites to inhabit dark matter halos with masses between one to ten billion solar masses at the time they fell into the Milky Way. Here we use a modelling approach, independent of cosmological simulations, to obtain a preinfall mass of 360 (+380,-230) million solar masses for one of the Milky Way's satellites: Carina. This determination of a low halo mass for Carina can be accommodated within the standard model only if galaxy formation becomes stochastic in halos below ten billion solar masses. Otherwise Carina, the eighth most luminous Milky Way dwarf, would be expected to inhabit a significantly more massive halo. The implication of this is that a population of "dark dwarfs" should orbit the Milky Way: halos devoid of stars and yet more massive than many of their visible counterparts.Comment: 5 pages, 3 figures, 1 table, and supplementary material availabl