Development of a universal stress sensor for graphene and carbon fibres

Carbon fibres are a significant volume fraction of modern structural airframes. Embedded into polymer matrices, they provide significant strength and stiffness gains by unit weight compared with competing structural materials. Here we use the Raman G peak to assess the response of carbon fibres to the application of strain, with reference to the response of graphene itself. Our data highlight the predominance of the in-plane graphene properties in all graphitic structures examined. A universal master plot relating the G peak strain sensitivity to tensile modulus of all types of carbon fibres, as well as graphene, is presented. We derive a universal value of - average - phonon shift rate with axial stress of around -5ω0 -1 (cm -1 Mpa-1), where ω0 is the G peak position at zero stress for both graphene and carbon fibre with annular morphology. The use of this for stress measurements in a variety of applications is discussed. © 2011 Macmillan Publishers Limited. All rights reserved.

Modelling cognitive impairment to improve universal access

The purpose of this study is to develop a model of cognitive impairment to help designers consider the range of issues which affect the lives of people living with such impairment. A series of interviews with experts of cognitive impairment was conducted to describe and assess the links between specific medical conditions, including learning disability, specific learning difficulties, autistic spectrum disorders, traumatic brain injury and schizophrenia, and the types of cognitive impairment associated with them. The results reveal some of the most prevalent and serious types of impairment, which - when transformed into design guidance - will help designers make mainstream products more inclusive also for people with cognitive impairment. © 2011 Springer-Verlag.

Universal access and assistive technology

This book contains the proceedings of the first Cambridge Workshop on Universal Access and Assistive Technology (CWUAAT), incorporating the fourth Cambridge Workshop on Rehabilitation Robotics, held in Cambridge, England in March 2002.

Steady-state modelling of the universal exhaust gas oxygen (UEGO) sensor

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. © 2012 IOP Publishing Ltd.