Ceri Evans

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The authors investigated factors that may determine whether perpetrators of violent crime develop intrusive memories of their offense. Of 105 young offenders who were convicted of killing or seriously harming others, 46% reported distressing intrusive memories, and 6% had posttraumatic stress disorder. Intrusions were associated with lower antisocial(More)
This paper examines the estimation of a global nonlinear gas turbine model using NARMAX techniques. Linear models estimated on small-signal data are first examined and the need for a global nonlinear model is established. A nonparametric analysis of the engine nonlinearity is then performed in the time and frequency domains. The information obtained from(More)
The linear multivariable modelling of an aircraft gas turbine is presented. A frequency-domain identification method is employed to estimate a family of models from engine data at a range of operating points. It is found that the fuel feed to shaft speed dynamics can be represented by second-order models. This matches the results obtained for the(More)
In this paper the orthogonal estimation algorithm is used to estimate a NARMAX model for an aircraft gas turbine. The performance of the model is validated using a range of small and large signal tests and by examining the model's static and dynamic characteristics. The NARMAX representation allows the direct mapping to the frequency domain by computing the(More)
This paper provides a comparison of techniques used to model the fuel flow to shaft speed relationship of a Spey gas turbine engine. Linear models are examined and the need for nonlinear modelling is justified. A technique based on nonparametric data analysis is proposed, to simplify the identification of a nonlinear model of the engine. A NARMAX model is(More)
OBJECTIVE This study aimed to validate brief intake screens for serious mental illnesses among New Zealand male prisoners. METHODS A prospective survey of consecutively admitted male remanded and sentenced prisoners was conducted across two New Zealand sites. Participants completed the Brief Jail Mental Health Screen (BJMHS) and the English Mental Health(More)