The universal exhaust gas oxygen (UEGO) sensor is a well-established device which was developed for the measurement of relative air fuel ratio in internal combustion engines. There is, however, little information available which allows for the prediction of the UEGO's behaviour when exposed to arbitrary gas mixtures, pressures and temperatures. Here we present a steady-state model for the sensor, based on a solution of the Stefan–Maxwell equation, and which includes a momentum balance. The response of the sensor is dominated by a diffusion barrier, which controls the rate of diffusion of gas species between the exhaust and a cavity. Determination of the diffusion barrier characteristics, especially the mean pore size, porosity and tortuosity, is essential for the purposes of modelling, and a measurement technique based on identification of the sensor pressure giving zero temperature sensitivity is shown to be a convenient method of achieving this. The model, suitably calibrated, is shown to make good predictions of sensor behaviour for large variations of pressure, temperature and gas composition.

The UK has incentivized the use of natural gas in heavy goods vehicles (HGVs) by converting to dual-fuel (DF) diesel-natural gas systems to reduce noxious and greenhouse gas emissions. Laboratory and on-road measurements of DF vehicles have demonstrated a decrease in CO 2 emissions relative to diesel, but there is an increase in greenhouse gas (CO 2 e) emissions because of unburned methane. Decreasing tailpipe emissions of methane via after-treatment devices in lean-burn compression ignition engines is a challenge because of low exhaust temperatures (∼400°C) and the presence of water vapor. In this study, six commercially available methane oxidation catalysts (MOCs) were tested for their application in DF HGV vehicles. Each MOC was characterized in terms of the catalyst platinum group metal (PGM) loading (both Pd and Pt), particle size, catalytic surface area, and Pd:Pt ratio. In addition, the washcoat surface area, pore volume, and pore size were evaluated. The MOC conversion efficiency was evaluated in controlled methane-oxidation experiments with varying temperatures, flow rates, and gas compositions. Characteristic-conversion efficiency correlations demonstrate that the influential MOC characteristics were PGM loading (both Pd and Pt), Pd:Pt ratio, washcoat surface area, and washcoat pore volume. With 90 % methane oxidation at less than 400°C in DF HGV exhaust conditions, sample 1 had the highest conversion efficiency because of a high PGM loading (330 g/ft 3 , 12,000 g/m 3), a 5.9 Pd:Pt ratio, a high alumina washcoat surface area of 20 m 2 /cm 3 , and 74-mm 3 /cm 3 pore volume. Additional studies showed increased MOC conversion efficiency with decreasing gas hourly space velocities (GHSVs) and increasing methane concentrations.

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In this paper, we utilise Jørgensen’s concept of what precarity does to make sense of stalled industrial development in a regional Australian community. In 2008–2009, a Chinese-owned multinational company proposed the development of an alumina refinery near Bowen, Queensland, offering residents the prospect of economic and local job growth, before the proposal was shelved in 2010. In direct contrast to the imagined ‘secure employment’ residents hoped the development would offer, past experiences of multinational developments had instead compounded economic and social precarity. Through a qualitative study of community and business perceptions in Bowen in 2008–2009, we explore how a regional community understands and resists histories and experiences of precarity. Despite recognising the changing economic and social structures that have contributed to insecurity, actors position themselves as malleable and aspirational potential workers, rather than resisting employment insecurity through collective means. This study provides a way of understanding the forces that impact aspirations of work in regional Australia and the gap between these aspirations and the tangible social impacts of a neoliberal economy.